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2008 Proceedings - FSHS Vol. 121

Abstracts

JORGE E. PEÑA, RITA E. DUNCAN, AND CHARLES W. MEISTER

Effect of Pesticides on Pests Affecting Tropical Fruit

Page 1-4

Selected pesticides were evaluated for control of the spider mites (Tetranychus spp.,) infesting bananas, sri-lankan weevil (Myllocerus undecimpustulatus) infesting mangoes, armored scales (Andaspis punicae and Chrysomphalus dyctiospermi) infesting mangoes, and Persea mite (Oligonychus perseae) infesting avocados. A. punicae has an armor usually covered with the outer layers of the bark and regularly is located near lenticels. C. dyctiospermi is an economic pest in Florida to fruit and ornamentals. Myllocerus undecimpustulatus is a weevil introduced into the USA during 2000, and it has since spread to different counties in the state, causing damage to fruit crops and ornamentals. The Persea mite, Oligonychus perseae, is native to Mexico. It was discovered in Miami–Dade County during June 2007. Spider mites, Tetranychus spp., cause damage to the foliage of bananas. All trials were conducted at the Tropical Research and Education Center. We discuss the effectiveness and shortcomings of the tested products.
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IRWIN DUARTE S.¹, LIGIA NUÑEZ B.², JORGE E. PEÑA³*, AND LIBARDO PINTO4

Biology, Parasitoids, and Damage of Leptoglossus zonatus and Leptoglossus gonagra (Heteroptera: Coreidae) on Citrus

Page 5-9

The appearance of watery lesions on citrus fruits in Santander–Colombia, coincided with high densities of Leptoglos­sus zonatus (Dallas) and L. gonagra (F.) (Heteroptera: Coreidae) adults present on citrus groves in the same area. The current information on the biology and natural enemies of these coreids in Colombia is scarce, therefore, we report the life cycle of both species, the role of parasitoids of both pests, and their alternative host plants. The first instar nymph of both species survived on C. tangelo fruits, but the second instar failed to survive on these hosts. The life cycle of L. zonatus and L. gonagra using Phaseolus vulgaris as a substrate for the first and second instar and C. tangelo Ingram & Moore (Sapindales: Rutaceae) for the third to fifth instar resulted on the development of L. zonatus in 69.11 ± 3.4 d and the development of L. gonagra, on 69.7 ± 3.6 d. Several parasitoids were observed: the encyrtid Hexacladia sp. was found parasitizing 1.6% adults of L. gonagra; the syrphid Eristalis sp. was observed laying-eggs in a male of the same coreid and the tachinid fly, Trichopoda sp parasited 11% adults of L. zonatus. The alternant host plants were Solanum americanum Mill. (Solanales: Solanaceae), Melothria guadalupensis (Spreng.) Cogn, Momordica charantia (L.) (Cu­curbitales: Cucurbitaceae), Zea mayz (L.) (Poales: Poaceae), Psidium guajava (L.) (Myrtales: Myrtaceae), C. reticulata and C. tangelo. Statistical analysis of induced lesions to C. tangelo fruits, suggests that the presence of L. zonatus and L. gonagra are related to the presence of watery lesions on citrus fruits in the study area.
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LISA MYERS, JORGE E. PEÑA, RITA DUNCAN, AND JOHN B. HEPPNER

Microlepidoptera Complex Affecting Sapodilla (Manilkara zapota van Royen) in Florida

Page 10-13

The sapodilla (Manilkara zapota van Royen), also known as naseberry, nispero, zapote, zapotillo, chicozapote, native to Mexico and Central America is currently grown in southern Florida. Pests and diseases are not usually considered a major problem on sapodilla; however, the larva of the small moth Banisia myrsusalis has been reported as an occasional pest that causes extensive damage to sapodilla blooms in Florida. Damage to buds, flower drop, and damage to 70% of fruits have been observed (Peña, unpublished data). A preliminary survey of sapodilla groves was conducted from May to July 2002, since very little was known about this moth. The survey indicated the presence of lepidopterous pests feeding on the young leaves, flowers, or young fruits. Three Lepidoptera species were frequently encountered: Banisia myrsusalis (Lepidoptera: Thyrididae), Dichrorampha sapodilla (Lepdioptera: Tortricidae), and a Zamagiria sp. (Lepidoptera: Pyralidae). A test was conducted in 2006 to determine the efficacy of Fury, Novaluron, Venom, Danitol, Thiamethoxan, and Alverde for control of the sapodilla moths.
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MARK T. NICKUM, JONATHAN H. CRANE, BRUCE SCHAFFER, AND FREDERICK S. DAVIES

Response of Mamey Sapote (Pouteria sapota) Trees to Flooding in a Very Gravelly Loam Soil in the Field

Page 14-18

Mamey sapote trees are periodically subjected to flooding in southern Florida but their flood-tolerance is not known. ‘Magaña’ mamey sapote (Pouteria sapota) trees were planted on 11 May 2006 in the field in mounds of Krome very gravelly loam soil at the Tropical Research and Education Center in Homestead, FL. Before planting, the soil was scraped to the bedrock, and a water-resistant tarp and plastic sheet (barrier) was placed on the bedrock. Native soil was mounded on each barrier for each tree. The barrier edges were raised above the soil surface to form a pool so that trees could be individually flooded. The response of trees to flooding was tested in two separate trials on 6 Nov. 2006 to 9 Jan. 2007 (Fall–Winter) and 23 Apr. to 11 June 2007 (Spring–Summer). Trees were divided into control (nonflooded) and flooded treatments. In the Fall–Winter Trial, flooding resulted in leaf epinasty after 2 weeks and reductions in net CO2 assimilation (A) after 3 weeks; however, leaf abscission was not higher for flooded trees than nonflooded trees. By the end of 70 days of flooding, only one tree (12%) died. In the Spring–Summer Trial, A was significantly lower for flooded trees than nonflooded trees by the beginning of week 2. By the end of week 4, four out of eight flooded trees had no leaves and one had wilted leaves, while three trees were still in good condition. Six of the flooded plants were infected with Pythium splendens root rot, which was likely the cause of death. Therefore, mamey sapote appears moderately tolerant to flooding in a very gravelly loam soil. However, more work is needed to separate tree decline due to flooding from that due to P. splendens infection in this soil.
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JONATHAN H. CRANE, BRUCE SCHAFFER, YUNCONG LI, EDUARD A. EVANS, WANDA MONTAS, AND CHUNFANG LI

Effect of Foliarly Applied Acids and Ferrous Sulfate on Leaf Ferrous Iron Content and Leaf Greenness of Lychee Trees

Page 19-23

Iron deficiency is a major nutritional problem of lychee trees (Litchi chinensis Sonn.) grown in calcareous soils. Applica­tions of chelated iron (Fe) to calcareous soil are efficacious but very expensive. The effects of foliarly applied organic acids, organic acids plus ferrous sulphate (FS), or a chelated Fe (EDDHA) soil drench on Fe nutrition of 18-month-old ‘Mauritius’ lychee trees in containers and 8-year-old ‘Kaimana’ lychee trees in calcareous soil in an orchard in southern Florida were investigated during 2006. All foliar treatments included the organosilicone adjuvant Freeway®. Trees in containers were sprayed at 2-week intervals six times with one of the following foliar treatments: ascorbic acid alone (AA), citric acid (CA), sulphuric acid (SA), ascorbic acid plus FS (AA+Fe), citric acid plus FS (CA+Fe), or sulphuric acid plus FS (SA+Fe). Additional treatments were application of chelated Fe (EDDHA) as a soil drench applied once at the beginning of the treatment period or trees receiving no Fe (Control). Trees in the orchard were sprayed four times at 14- to 18-day intervals with one of the following treatments: AA, AA+Fe, CA+Fe or SA+Fe or soil drenched two times with chelated Fe (EDDHA) or the control. Leaf chlorophyll indices were determined with a SPAD meter. For trees in containers, SPAD, and leaf total and ferrous Fe content were significantly higher in trees receiving all foliar acid+Fe and EDDHA treatments compared to trees in the acid alone and control treatments. Similarly, SPAD values and leaf total and ferrous Fe content of leaves of orchard trees were significantly higher for all foliar acid+Fe treated leaves compared to EDDHA, AA, or control treatments. Economic analysis indicated that foliar applications of acid+Fe were 51% to 75% less costly than soil applications of EDDHA.
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A.R. RAFIE AND CHRIS MULLINS

Challenges for High Tunnel Production of White Guava in Southern Virginia

Page 24-25

Guava, Psidium guajava L. is a tropical and subtropical fruit with many varieties grown in different countries. The traditional pink-flesh guava is mainly used for processing purposes and has yet to cross over to American consumers.  The white-flesh guava, a mildly sweet fruit with a crunchy texture is eaten when fruit color reaches a yellowish green stage, and has attracted attention in recent years. In southern Florida, the white guava variety is appreciated among some American consumers. Growers in Virginia are always looking for new crops with market potential. In response to this, a study was conducted to evaluate the possibility of growing white guava under high tunnel conditions in southern Virginia. One-year-old trees were planted in Nov. 2007 and Jan. 2008. Trees initiated blooming in Apr. 2008 and fruits were harvested starting the last week of Sept. 2008.
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SARA RAMOS, MARÍA DEL CARMEN LIBRÁN, ANGEL GONZÁLEZ, ROBERT ROUSE, PHIL STANSLY, ANNETTE WSZELAKI, J. PABLO MORALES-PAYÁN, AND EVELIO HERNANDEZ

Control of the Caribbean Fruit Fly on Three Peach Cultivars in Adjuntas, Puerto Rico

Page 26-27

Low-chill peach cultivars (‘Flordaprince’, ‘TropicBeauty’, and ‘Flordaglo’) were evaluated in two sites (Beneficiado and Montaña) in Adjuntas, PR. Fruit yield and quality were severely reduced by Caribbean fruit fly [Anastrepha sus­pensa (Loew)], which had not been previously reported in peaches in Puerto Rico. The objective of this study was to evaluate a control method for this species. To evaluate fruit fly control, a paired design was used. Three pairs of trees per cultivar (similar yield) were chosen in the two peach sites. One of the two sites was sprayed weekly with GF-120 NF Naturalyte® (Dow AgroSciences). Mature fruits were harvested randomly from each tree on four sampling dates. A lower number of fruit fly larvae were observed in fruits from treated trees. Differences in the number of fruit fly larvae between pairs within each cultivar were evaluated by a paired t test. Statisical analysis results demonstrated the efficiency of the treatment to control A. suspensa in the evaluated peach cultivars. By increasing the treated area, efficacy should improve.
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GARY K. ENGLAND, ELENA M. RHODES, AND OSCAR E. LIBURD

Thrips Monitoring in Blueberries

Page 28-29

Flower thrips belonging to the genus Frankliniella affect both rabbiteye and southern highbush blueberries. Frankliniella bispinosa is one of the most destructive pest of Florida blueberries (Arevalo et al., 2006). These tiny insects with yellow­ish to orange coloration and fringed wings progress through two actively feeding larval instars and two inactive instars (often called pupae) during their short life cycle of 18 to 22 days. Thrips damage blueberry flowers and developing fruit by the feeding activities of larvae and adults. Oviposition by female adults and the eventual emergence of larvae can also result in significant damage. Monitoring flower thrips populations in commercial blueberry fields can be a strategy to determine if insecticide applications are necessary. One method of monitoring is to place white sticky traps within the canopy of commercial blueberries during the flowering period. It is recommended that four traps per acre with two in the interior and two on the border portions of the planting. Check traps once per week to determine if the population is approaching the treatment threshold. A more labor intensive method is to collect 20 blueberry flowers per acre and count the thrips present. Studies sponsored by IPM Florida were conducted in commercial blueberry fields in spring 2006 and 2007 to evaluate monitoring methods. The data indicated differences in thrips counts in various commercial blueberry cultivars evaluated in the trial, with ‘Emerald’ having highest counts on sticky traps.
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OSCAR E. LIBURD, TERESIA W. NYOIKE, AND HECTOR A. ARÉVALO

Monitoring and Phenology of Thrips in Southern Highbush Blueberries

Page 30-32

Flower thrips damage floral tissues and reduce yield in southern highbush blueberries, but information on species complex and phenology is limited. During 2004 and 2005, we studied thrips species complex and phenology on two 1-ha commercial southern highbush blueberry farms. White sticky traps and blueberry flowers were used as our sampling units. Ten traps were placed randomly ~31 m apart throughout each 1-ha farm located in south-central and north-central Florida, respectively. Traps were collected weekly from flower opening to fruit set and thrips were removed and individually slide mounted for identification. Similarly, five flower-clusters (about five flowers per cluster) were collected weekly from the same bushes where the traps were deployed. The thrips were removed from the flowers and preserved in 50% alcohol before being slide-mounted for identification. Voucher specimens from traps and flowers were sent to the Florida State Collection of Arthropods (FSCA) in Gainesville, FL. Among the thrips species recorded at both sites, the Florida flower thrips [Frankliniella bispinosa (Morgan)] was the most commonly encountered species, accounting for >65% of the thrips in flowers and >83% of the thrips on sticky traps. Other species recorded included F. fusca, F. occidentalis, and Thrips hawaiiensis, which individual species accounted for less than 13% of the thrips found in flowers and on sticky cards. Sporadic catches (fewer than two specimens) included Haplothrips victoriensis, F. kelliae, and F. schultzei. Overall thrips abundance was highly correlated with flower development.
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PETER C. ANDERSEN, JEFF G. WILLIAMSON, E. PAUL MILLER, AND PAUL M. LYRENE

Performance of Highbush Blueberries in North Florida

Page 33-35

A southern highbush blueberry (Vaccinium corymbosum L.) planting was initiated at the NFREC–Quincy during Spring 2003. The experimental planting consisted of ‘Bluecrisp’, ‘Emerald’, ‘Jewel’, ‘Millennia’, ‘Misty’, ‘O’Neal’, ‘Sharpblue’ and ‘Star’. Plants were mulched with approximately a 10-cm layer of pine bark and were supplied with drip irrigation. Overhead freeze protection was not applied. Yield per bush, berry weight, and soluble solids was measured in 2004; however, because of herbivory by crows in 2005 yields were not determined and only samples of berries were evalu­ated for berry weight and soluble solids. From 2006 to 2008, yields were rated before berry ripening and before crow herbivory. During 2004, yields per bush varied between 19 g for ‘Misty’ and 1250 g for ‘Star’. ‘Emerald’ and ‘Star’ produced a consistent crop in 2006 (62% to 63% of a crop) and 2007 (49% to 50% of a crop). In 2008, ‘Emerald’ had a small crop of large berries and ‘Star’ had a moderate crop, although berry size was small. ‘Millennia’ produced a moderate crop in 2004, 2006, and 2007 and a small crop in 2008. Yield rating of ‘Misty’ was highest of all cultivars in 2007, but was low in 2006 and moderate in 2008. ‘O’Neal’ produced about 50% of a crop from 2006 to 2008. ‘Jewel’ and ‘Sharpblue’ had low yield ratings during all years. Berry weights averaged at least 1.4 g in all years except 2007. Average soluble solids were higher in 2006 (13.2 °Brix), 2007 (12.0 °Brix) and 2008 (14.5 °Brix) compared to 2004 (9.8 °Brix) and 2005 (8.9 °Brix). ‘Bluecrisp’ had the highest soluble solids in 2006 (15.2 °Brix) and 2008 (16.3 °Brix), whereas ‘Emerald’ had the highest soluble solids in 2007 (13.9 °Brix). Overall berry quality was highest for ‘Bluecrisp’, although yield was not as high as some of the cultivars. Percentage survival ranged from 53% (‘Jewel’) to 100% (‘Emerald’). Bush size was largest for ‘Star’ and ‘O ‘Neal’ and smallest for ‘Sharpblue’.
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ALICIA WHIDDEN

Commercial Blueberry Production Methods in Hillsborough County

Page 36-37

More inquiries are received on starting up a commercial blueberry operation than are received for any other fruit or vegetable commodity in Hillsborough County. Hillsborough County is located along the west central coast of the state and is in climate zone 9. Florida Ag Statistics records show there were around 1,500 acres of blueberries in the entire state in 2000–01. The 2004–05 Florida Ag Statistics reported 2,500 acres in the state. In 2006 Hillsborough County had 325 acres with approximately half of the acreage established in the last 10 years or less. The size of the farms in the county varies from ¼ acre to almost 30 acres with most being 5 acres or less. The south central part of the state has a unique market window from mid-March to early May. This is the only place in the world with fresh blueberry production at that time of year. This has allowed growers to sell at a high price. Many new growers who may or may not have growing experience are attracted to the hopes of continued high returns and the ability to be competitive in the market even though they may only be a small farm. Growers in this area are using three cultural management systems. The three systems are mulched rows, broadcast mulch high intensity plantings, and container production. Container production has been very popular in this area. Reasons for using each system and pros and cons of each will be discussed.
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XIA XU, JIANG LU, DANAE DALLING, HUANG HONG, CLIFFORD LOUIME, ZHONGBO REN, FITZ BRADLEY, AND RASHAD REED

Application of Embryo Rescue in Grape (Vitis) Cultivar Development

Page 38-40

Interspecific hybridization and stenospermocarpic seedless grape cultivars from Vitis vinifera L. or its hybrids have been widely used in Florida grape cultivar development. Unfortunately, interspecific sternospermocarpic hybrid em­bryos aborted prematurely and failed to develop into plants. Immature ovule cultures were conducted to rescue such embryos and recover the hybrid plants for improving grape breeding efficiency. Immature ovules were excised from berries 6 to 8 weeks after pollination and then cultured on Emershad and Ramming (ER) medium supplemented with 0.05 g·L–1 casein hydrolysate, 0.05 g·L–1 inositol, 1.21 g·L–1 cysteine, 0.98 g·L–1 MES [2-(N-Morpholino) ethanesulfonic acid] for 2 months, followed by dissecting embryos and cultured on Lloyd and McCown woody plant (WP) medium for germination. Ovules cultured on ER medium plus 0.2 mg·L–1 BAP (6-benzylaminopurine), Nitch and Nitch (NN) medium supplemented with 0.2 mg·L–1 NAA (α-naphthaleneacetic acid) and 0.5 mg·L–1 GA (gibberellin) were also tested for direct germination. It was found that using ER medium for ovules culture followed by WP medium for embryo germination was the most efficient approach for recovering aborted embryos. For example, 57.3% of hybrid embryos were rescued from ‘O47-3-7’ x ‘Orlando Seedless’, and 50.0% from its reciprocal cross. However, direct in vitro germination of the aborted embryos without ovule dissecting was found less success.
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ROBERT C. HOCHMUTH, LEI LANI DAVIS, WANDA L. LAUGHLIN, AND APRIL L. WARNER

Chestnut (Castanea sp.) Cultivar Evaluations for North Florida

Page 41-42

The chestnut (Castanea sp.) is a unique tree crop with potential as an alternative crop for small farmers in North Florida. Few tree crops have had more historical significance than the chestnut. The American chestnut was one of the common trees in eastern United States forests until the early to mid 1900s. Chestnut blight (Cryphonectria parasitica) was accidentally introduced to the US from the Orient in 1904 and killed nearly every American chestnut (C. dentate) in the US by the 1940s. Less than 1% of the world production of this nut now occurs in the United States. Chestnuts are gaining popularity in response to its attributes of a high quality, nutritious, fresh, local product, low in fat. Chinese chestnut (C. mollissima) and Japanese chestnut (C. crenata) are resistant to blight. In Florida, varieties of Chinese and American chestnut crosses are being successfully grown, as well as Chinese chestnut cultivars. A chestnut cultivar trial was established at the North Florida Research and Education Center–Suwannee Valley near Live Oak, FL in 1989. The planting included seven cultivars planted in a 30 × 30 ft arrangement. The chestnut crop in this trial was harvested in 2006 and 2007 and nuts were counted and weighed to obtain total yield and nut size for each cultivar.
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PAUL MILLER, JEFFREY G. WILLIAMSON, AND LUIS MEJIA

Preliminary Results on the Performance of Low-chill Peach Cultivars in North-central Florida

Page 43-45

Fruit yields were taken for 1 or 2 years from young ‘UFSun’, ‘Gulfking’, ‘Flordaprince’, ‘Earligrande’, ‘Flordaglo’, ‘Flordastar’, ‘Flordaking’, ‘Tropic Snow’, ‘Tropic Beauty’, ‘UF2000’, ‘Flordabelle’, and ‘Rayon’ peach, and ‘Sunraycer’, ‘Sunbest’, and ‘Sunmist’ nectarine trees. The study was conducted at the Plant Science Research and Education Unit (PSREU) in northern Marion County near Citra, FL. Fruit were harvested in 2007 and 2008. This area can produce low-chill peaches and nectarines during the last week of April through the middle of June. The earliest-ripening cultivars were ‘UFSun’, ‘Gulfking’, ‘Flordaprince’, ‘Sunbest’, ‘Earligrande’ and ‘Flordaglo’, which began ripening in early to mid May in 2008. ‘Flordastar’, ‘Flordaking, ‘Sunraycer’, and ‘TropicSnow’ can be early with early fulfillment of their chilling requirements, but tended to be later than expected, or variable in this study. Overall, fruit ripening was later than expected during 2007 due to low or interrupted chill accumulation. Fruit size was highly variable among cultivars and between years but tended to be inversely related to crop load. Fruit size ≥2.5 inches (diameter) is achievable with a large proportion of fruit for several cultivars when timely and thorough fruit thinning is used to adjust crop load.
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JEFFREY G. WILLIAMSON, TODD W. WERT, JOSE X. CHAPARRO, PAUL MILLER, AND R.E. ROUSE

Flower and Vegetative Bud Set of Four Low-chill Peach Cultivars at Three Locations in Florida

Page 46-48

Vegetative and floral bud set of four low-chill peach cultivars (‘Flordaprince’, ‘Flordaglo’, ‘UFGold’, and ‘TropicBeauty’) were evaluated at three locations ranging from north-central to southwestern Florida. Nodes were categorized as either blind (no buds), mixed (vegetative and floral buds), or vegetative (vegetative buds only). The percentages of each node type were determined from representative shoots of each tree at each location. Generally, higher proportions of blind nodes occurred in central and southwestern Florida and more mixed nodes were observed at the north-central Florida site. ‘TropicBeauty’ had a larger percentage of blind nodes than the other cultivars. Higher temperatures during bud formation probably contributed to high percentages of blind nodes and the relatively low percentages of mixed nodes observed at the central and southwest locations when compared to the north-central location. Certain genotypes appear to have a predisposition for the formation of blind nodes. Advanced selections that have potential adaptation to a wide diversity of tropical or subtropical climates need to be tested in multiple locations to evaluate blind node formation.
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JEFFREY G. WILLIAMSON, TODD W. WERT, JOSE X. CHAPARRO, PAUL MILLER, AND ROBERT E. ROUSE

Climate Affects Fruit Shape of Four Low-chill Peach Cultivars in Florida

Page 49-51

Fruit of four low-chill peach [Prunus persica (L.) Batsch] cultivars were evaluated for blossom end shape and suture deformation at three locations ranging from north-central to southwest Florida. During 2005, representative fruit of each cultivar were measured at all locations for cheek diameter, suture diameter, and tip protrusion. Suture deforma­tion was calculated by dividing suture diameter by cheek diameter for individual fruits. Fruit tips were subjectively rated as being protruded, flush, or recessed. Protruding tips and suture deformation were more pronounced at the southwest location than at the north-central or central locations. Overall, ‘TropicBeauty’ had more protruding tips than the other cultivars. It is likely that warmer temperatures at the southwest location during fruit development increased the incidence of protruding tips and pronounced sutures.
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HUMBERTO A. LEBLANC AND RICARDO O. RUSSO

Carbon Sequestration in an Oil Palm Crop System (Elaeis guineensis) in the Caribbean Lowlands of Costa Rica

Page 52-54
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JACOB SEARCY, FRITZ ROKA, AND THOMAS SPREEN

Scheduling the Harvest of Florida Oranges to Maximize Juice Production

Page 55-60

Successful adoption of mechanical harvesters by the Florida citrus industry will require changes to the current op­erational systems of fruit production, harvesting, and juice processing. These operational changes have the potential to impact financial returns throughout the market. Clearly defining the relationships among the biological changes in the fruit, industry operational decisions, and economic returns from operation will contribute to improving the future of citrus harvesting in Florida. The primary objective of this research is to develop a harvest scheduling model for the Florida orange juice production industry that optimizes juice production while incorporating biological and logisti­cal constraints that face both growers and processors. The first step in this research process is to develop a biological model of expected fruit maturity and yield based on fruit variety, tree age, and geographic location that maximizes total pound-solid production. The second step is to extend the biological model by incorporating current harvesting and processing limitations along with estimating the impacts of these restrictions on production and economic returns. Scheduling of harvest will be determined by optimizing pound-solid production under these harvesting and processing limitations.
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GERMAN BLANCO, FRITZ ROKA, JACQUELINE BURNS, AND RICHARD KILMER

Economic Value of an Abscission Compound for Mechanically Harvested Late-season ‘Valencia’ Oranges

Page 61-64

This paper compares estimated economic values of mechanically harvesting ‘Valencia’ [Citrus sinensis (L.) Osb.] during the late season without adverse yield impacts, against the estimated cost of development and registration of the abscission compound, CMNP (5-chloro-3-methyl-4-nitro-1-H-pyrazole). The basis of this analysis is a “benefit-cost” model that compares the discounted cash flows of public expenditures against projections of future private benefits of extending mechanical harvesting into late May and June with CMNP application. The estimated net present value (NPV) of cash flows, over a 10-year planning horizon with an assumed interest rate of 10%, was $38 million. The public investment for CMNP registration and development had a positive internal rate of return (IRR) of 32.64% and a payback period of 4.8 years from 2008. Thus, benefits resulting from the application of abscission compound for mechanically harvest­ing late-season ‘Valencias’ more than offset the cost of R&D and registration.
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BOB EBEL, KELLY MORGAN, PETER NEWMAN, JACKIE BURNS, AND JIM SYVERTSEN

Effects of Short-term Drought Stress of ‘Hamlin’ and ‘Valencia’ Trees and CMNP Application on Fruit Detachment Force, Fruit Drop, and Fruit Quality

Page 65-68

Two studies, one on ‘Hamlin’ and the other on ‘Valencia’ trees, were conducted to determine if short-term drought stress affects efficacy of 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP) for loosening fruit as an aid for mechanical harvesting. ‘Hamlin’ orange trees were drought stressed in late February by withholding irrigation for 5 days (control), 12 or 19 days before harvest and ‘Valencia’ orange trees were drought stressed in late April by withholding irrigation 0 (control), 4 or 7 days before harvest. Soil moisture, leaf conductance, transpiration and stem water potential were lower for the drought treatments compared to the controls. There was no significant interaction between drought stress and CMNP on fruit detachment force (FDF) or fruit drop. CMNP substantially decreased FDF and fruit drop; however, drought stress did not. These results indicate that drought stress from 7 to 19 days does not alter efficacy of CMNP.
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WILLIAM R. LUSHER, JOHN L. JACKSON, AND KELLY T. MORGAN

The Florida Automated Weather Network: Ten Years of Providing Weather Information to Florida Growers

Page 69-74

The Florida Automated Weather Network (FAWN) is a statewide system of 35 automated weather observing sites that collect data every 15 minutes. The data, along with several calculated products and weather-related tools, are delivered to the public via the Internet at <http://fawn.ifas.ufl.edu>. Data can also be retrieved via telephone voice message system. Data loggers, high-speed communication systems, sophisticated weather sensors, and expert personnel make it possible to establish real-time high-resolution weather observing systems such as FAWN. This paper details FAWN’s 10 years of providing valuable weather-related resources to its many users by highlighting how FAWN began, its current operational structure, data collection and access, products, public outreach, and contributions to the citizens of Florida.
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JOHN L. JACKSON, KELLY T. MORGAN, AND WILLIAM R. LUSHER

Citrus Cold Weather Protection and Irrigation Scheduling Tools Using Florida Automated Weather Network Data

Page 75-80

Weather-related information is essential to Florida’s agricultural producers for making important decisions. Citrus growers, in particular, routinely monitor current weather conditions to make informed decisions regarding the use water for irrigation and cold protection as well as the application of chemicals. Real-time monitoring of air and wet bulb temperatures is critical in cold protection and determining daily evapotranspiration rates can significantly impact irrigation scheduling. The Florida Automated Weather Network (FAWN), a program of the University of Florida Insti­tute of Food and Agricultural Sciences (UF/IFAS), provides growers with a variety of weather-related tools that can aid them in making these decisions. The FAWN Cold Protection Toolkit assists growers in estimating minimum overnight temperatures, tracking of forecasts, estimating evaporative cooling potential, and determining the temperature at which to shut down frost-protecting irrigation; all based on real-time weather data. The FAWN Citrus Microsprinkler Irrigation Scheduler can assist growers in determining the appropriate number of days between irrigation, irrigation run-time based on evapotranspiration rates and specific grove spacing data, irrigation system design, and soil type. In addition there is a “Microsprinkler System Maintenance Guide” to assist users with questions regarding the delivery system. These tools can be found at: http://fawn.ifas.ufl.edu/tools.
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SHIV D. SHARMA, MEGH SINGH, AND STEVE H. FUTCH

Glyphosate and Carfentrazone Herbicides for Difficult-to-control Weeds in Citrus

Page 81-84

Experiments were conducted in greenhouse and field to examine the efficiency of tank mixing glyphosate and carfentra­zone to control the difficult-to-control weeds of citrus, Brazil pusley (Richardia brasilienses) and dayflower (Commelina bengalensis). Glyphosate was applied at 2145 and 3220 g a.i./ha and carfentrazone at 17.7 and 35.5 g a.i./ha as sole and tank mixed applications. In a greenhouse study, percent control of Brazil pusley and dayflower was increased succes­sively to 100% by the fourth week with the application of the lower rate of glyphosate examined in greenhouse study. Application of the lower rate of carfentrazone at 17.7 g a.i./ha achieved 100% control of dayflower, but on Brazil pusley, carfentrazone had only a negligible effect. It was not possible to distinguish any synergistic effect on the phytotoxicity of their tank mixed application. In the field, application of glyphosate and carfentrazone at higher rates had significantly better control of dayflower than the lower rates. The control of Brazil pusley was significantly better with the higher rate of glyphosate compared to the lower rate. Carfentrazone had a negligible effect on the control of Brazil pusley. Tank mix application of glyphosate and carfentrazone had a synergistic effect on the control of dayflower. Tank mix did not show any added effect on the phytotoxicity of Brazil pusley. Application of tank mix glyphosate and Landmaster II (glyphosate + 2,4-D) provided similar control in greenhouse and field as achieved by a tank mix of glyphosate and carfentrazone. The study indicated that the effect of carfentrazone or glyphosate varied with the weed species. However, tank mix application of glyphosate and carfentrazone had some positive control effects on both plants.
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JUAN MANUEL CEVALLOS-CEVALLOS, EDGARDO ETXEBERRIA, RUSSELL ROUSEFF, AND JOSÉ I. REYES-DE-CORCUERA

Metabolite Profiling of Healthy and Huanglongbing-infected Citrus Leaves

Page 85-89

Citrus huanglongbing (HLB) is currently the greatest threat to the Florida citrus industry. Many efforts are focused on the development of methods to detect this disease in early stages. This research focuses on the characterization of metabolite differences between healthy and HLB-infected leaves. A visual infection scale based on the appearance of infected ‘Valencia’ orange leaves was created to determine the intensity of the symptoms. Results obtained from HPLC-MS showed three marked chromatogram zones in which there was a significant variation of certain compounds with increasing HLB infection scale value. Some early and mid eluting compounds had an increase in peak areas, whereas other late eluting compounds such as chlorophyll derivatives had a reduction in peak areas with increasing infection scale value. Most of the compounds showed mass to charge ratio values between 50 and 800 units. GC-MS, HPLC-MS-MS, and 2D electrophoresis are currently being performed for better compound identification and protein characterization. Further research is needed to differentiate HLB-induced variations from other stress-induced varia­tions that may cause similar changes in citrus leaves.
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STEVEN ROGERS

How the Florida Citrus Production Research Advisory Council Works with Other Industry Organizations for Solutions to the Greening Crisis

Page 90-96

The Florida Citrus Production Research Advisory Council (FCPRAC) operates under the Florida Citrus Production Research Marketing Order which was approved in referendums in 1991, 1997, and 2004. This order allows growers to tax themselves up to 1 cent per box of fruit and direct those funds to help solve citrus production problems. Funds are awarded as competitive grants selected from proposals submitted each year to the 14 grower representatives of the FCPRAC. This year, the Florida Legislature and the Department of Citrus contributed to increase funds to $7.2 million, resulting in over 100 research projects being funded. The primary focus of recent research is citrus greening (sometimes called HLB). With the urgency in controlling this disease, FCPRAC is reorganizing to make it easier to cooperate with outside entities for managing and funding projects. One new cooperator is the U.S. National Academy of Sciences, who will help ensure scientific quality in funded research. This paper discusses recent developments in FCPRAC activities and how scientists and other stakeholders can participate in these programs. A new real-time web reporting system is also presented that allows scientists to provide ongoing information about their research programs.
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TIMOTHY M. SPANN AND W. CHRIS OSWALT

Citrus Greening Effects on Fruit Size Distribution and Yield in Citrus Trees

Page 97-99

Citrus greening disease or huanglongbing (HLB) is a bacterial disease caused by the phloem-limited bacteria Candidatus Liberibacter spp. The disease causes phloem collapse, which leads to a number of symptoms expressed in leaves and fruit of infected trees. Fruit symptoms include small fruit size, misshapen and lopsided fruit, an inverted color change and off-flavors in the fruit. It is important to keep off-flavored greening-affected fruit from entering the processing plant where they could taint large volumes of juice, as they would be unacceptable to consumers. We hypothesized that there is a significant difference in the fruit size distribution, more heavily weighted to smaller fruit, in greening-infected trees than healthy trees. This change in size distribution caused by greening would reduce yield and might be used to grade out affected fruit at harvest from a potentially infected area. Additionally, a load of fruit with a disproportionately high number of small fruit could be an indicator of possible greening infection, thus helping to direct scouting efforts.
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ABEER KHALAF, VICENTE J. FEBRES, GLORIA A. MOORE, AND FREDERICK G. GMITTER JR.

Progress in Manipulating Citrus Defense Pathways in Favor of Citrus Resistance against Greening and Canker

Page 100-103

Understanding the mechanisms of plant–pathogen interaction is believed to be key to resolve the existing crop disease crisis. Molecular advances have facilitated the discovery and study of genes associated with natural defense pathways in a number of model systems. In our laboratories, citrus homologues of vital defense genes have been identified using comparative analysis and their expression has been characterized. In addition, differential gene expression during infection with citrus canker has been examined. Both approaches have facilitated the study of defense responses in citrus. The better understanding of these natural defense pathways has allowed plant-derived genes to be used to in­duce disease resistance. These recent discoveries as well as strategies for their practical application in citrus breeding are discussed in this review.
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D.G. HALL, T.R. GOTTWALD, N.C. NGUYEN, K. ICHINOSE, Q.D. LE, G.A.C. BEATTIE, AND E. STOVER

Greenhouse Investigations on the Effect of Guava on Infestations of Asian Citrus Psyllid in Grapefruit

Page 104-109

Reports from Vietnam indicate interplanting guava with citrus reduces infestations of Asian citrus psyllid (ACP) (Diaphorina citri) in citrus. We therefore conducted cage studies in a greenhouse to assess the effect of different guava cultivars on adult ACP mortality and settling behavior on citrus (young potted grapefruit). The effects of cotton and tomato were also evaluated in some tests as non-citrus, neutral host species. Survival of adult ACP confined to potted guava in no-choice situations was reduced as compared to survival on potted grapefruit. However, adult survival was also reduced when they were confined to potted cotton or tomato. Adult ACP released into cages containing only citrus generally moved faster to citrus than when either ‘White’ guava or cotton was present. Greater numbers of adults were consistently observed on citrus over time in cages with only citrus as compared to in cages with citrus in the presence of guava or cotton. This may have been due to differences in the total plant surface area in cages with citrus alone compared to citrus caged with another plant. Mortality rates of adults were increased in cages containing both citrus and guava in one of two studies. While significant reductions in infestations of adults on young grapefruit sometimes occurred in cages containing both citrus and guava in the greenhouse, the reductions were not enough to verify the Vietnamese guava effect.
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RYAN ATWOOD AND LUKASZ STELINSKI

Evaluation of Low Volume Application Technologies for Asian Citrus Psyllid (Diaphorina citri Kuwayama) Control: Initial Results

Page 110-112

The occurrence of citrus greening (huanglongbing) disease in Florida mandates the effective control of the insect vector, Asian citrus psyllid (Diaphorina citri Kuwayama). Anecdotal evidence suggests that reducing psyllid popu­lations via insecticide application may slow the rate of disease spread. Due to its speed and low cost, growers have experimented with low volume application technology for controlling psyllids. The overall objective of this study was to evaluate ultra low volume (ULV, fogging) applicators for control of D. citri. Efficacy with ULV technologies was equivalent to that with standard airblast applications. The duration of efficacy was much longer if a dormant winter spray was applied rather than a spray after spring flush. Pyrethroid, organophospate and insect growth regulator insecticides were effective against D. citri when applied as ULV sprays. Although fogging applications are effective, several pesticides known to be effective for psyllid control are currently not registered for application with ULV equipment. More research and appropriate regulatory changes to labels will be needed before fogging should be implemented commercially.
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JORGE E. PEÑA, R.E. DUNCAN, AND JOSEP A. JACAS

Dynamics of Mortality Factors of the Citrus Psyllid in Southern Florida

Page 113-117

Frequency of parasitoids and predators of Diaphorina citri was recorded during the morning and afternoon hours by observing activity and presence of natural enemies on a D. citri-infested orange jasmine (Murraya paniculata) hedges located in Homestead. The most common natural enemies during these observations were the predators Zelus longipes (Hemiptera: Reduviidae), Allograpta obliqua (Diptera: Syrphidae), Cicloneda sanguinea, Harmonia axyridides (Cole­optera: Coccinellidae), and Eriophora ravilla (Aranea: Araneidae). A survey for predators and parasitoids of D. citri was conducted from Nov. 2005 through May 2006 on limes (Citrus aurantifolia) and on orange jasmine in Homestead, Miami–Dade County. Percentage parasitism from Tamarixia radiata fluctuated between 0.85% and 7.74% for 2nd to 5th instar D. citri. The most common predators were syrphids and coccinellids. A re-validation of predator frequency was conducted from Mar. to Apr. 2007. At this time, reduviids, coccinellids and syrphids were the most common predators observed on M. paniculata. Orange jasmine could be acting as a constant and important surrogate reservoir of D. citri. Our surveys show a pattern of predator interference with parasitoids of D. citri. The role of alternant host plants and the interaction with natural enemies needs to be studied more thoroughly.
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JAMES H. GRAHAM, RUI P. LEITE, JR., HENRY D. YONCE, AND M. MYERS

Streptomycin Controls Citrus Canker on Sweet Orange in Brazil and Reduces Risk of Copper Burn on Grapefruit in Florida

Page 118-123

Reduced rates and frequency of copper as a bactericide to control citrus canker, caused by Xanthomonas citri spp. citri, could minimize risk of phytotoxicity (burn) to the fruit rind, development of bacterial resistance to copper, and reduce copper accumulation in the soil environment. Field trials in Brazil demonstrated that rates of 0.125x, 0.25x, and 0.5x copper hydroxide (CH), when applied at a 14-day interval, were as effective as the full rate (1.0x) of CH for control­ling canker on foliage and fruit. Lower rates of CH also reduced canker-induced fruit drop of moderately susceptible sweet orange cultivars. Streptomycin sulphate (SS, Agrimicina, 15% streptomycin + 1.5% oxytetracycline) was as effective as intermediate rates of CH, whereas oxytetracycline (OT, Mycoshield) was ineffective. At 21-day interval of application, SS combined with reduced rates of CH reduced fruit disease incidence and SS combined or alternated with CH significantly reduced fruit drop. In Florida on white grapefruit, CH and copper sulphate (CS) applied at 14- or 21-day intervals controlled canker on fruit, but caused considerable copper burn to the fruit rind. Alternation of SS (Firewall, 17% streptomycin) with a reduced rate of CS provided a similar reduction in diseased fruit with less copper burn than the full rate of CH or CS. In the 2006 and 2007 Florida trials, copper burn on grapefruit occurred in July. These incidents of phytotoxicity were preceded by below average rainfall from January to June leading to drought conditions by mid-summer.
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MANJUL DUTT, AHMAD OMAR, VLADIMIR ORBOVIC, GARY BARTHE, JULIE GMITTER, MONICA VASCONCELLOS, CHARLES DUNNING, AND JUDE W. GROSSER

Combating Huanglongbing and Canker via Genetic Engineering of Citrus

Page 124-129

Florida is the world’s third largest producer of citrus, behind Brazil and China. In recent years, this 9 billion dollar industry has been affected by two important diseases—citrus greening, also known as huanglongbing (HLB) and citrus canker. Both these diseases are caused by gram negative bacteria. Although canker can be managed by fol­lowing a canker suppression program, HLB affects all cultivated citrus varieties and cannot currently be controlled, except in the absence of the psyllid insect vector. Resistance to either HLB or canker is also not present in commercial orange and grapefruit cultivars. A strategy to produce resistant citrus is through genetic engineering by incorporat­ing resistance genes not found in citrus. We have successfully cloned several natural and synthetic antibacterial genes and made significant progress in introducing them into commercial sweet orange and grapefruit cultivars using both the standard Agrobacterium-mediated transformation system, and the protoplast/Green Fluorescent Protein (GFP) transformation system developed previously in our program. Genetic constructs containing promoters that target genes exclusively in the phloem tissue, where HLB resides, are also being utilized in efforts to minimize foreign gene expression in fruit or juice subsequently going to market. Techniques for construction and incorporation of the genes into citrus are discussed.
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L. GENE ALBRIGO

Citrus Yield, Fruit Quality, and Nutrient Levels Using Nitamin, CitriBlen, or Standard Ground Fertilizer

Page 130-133

Soluble ground-applied fertilizer (SGF at 150 lbs N/acre), a slow release fertilizer (CitriBlen at 90 lbs N/acre) and new products (Unity or Nitamin 30L at 120 or 150 lbs N/acre) that have some potential to slowly release N were compared as ground applied N sources for 4 years, from 6th to 10th year of ‘Hamlin’ orange and ‘Flame’ grapefruit trees. There were no significant yield differences using various N source fertilizer materials even though two of the treatments re­ceived products applied at lower rates. Overall yields were lower than expected, however, because the three hurricanes in 2004 passed over the planting and removed significant amounts of leaves and fruit in the first year. Subsequently, the trees never recovered to potential yield levels during this 4-year experiment. Pounds solids per box were higher in only one year for the SGF treatment, but soluble solids to acidity ratio was usually lower for this treatment due to higher acidity. Leached nitrates in the tree row where the fertilizers were applied were occasionally high after heavy rains but the fertilizer treatments did not greatly alter the average amount leached. A second test of foliar applied Nitamin 30L as a substitute for 60 lbs N/acre of the normal 180 lbs N/acre, did increase the yield of ‘Rhode Red Valencia’ trees in Lake Placid, FL. Juice quality and leaf N were not affected in the foliar test.
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ARNOLD W. SCHUMANN, JAMES P. SYVERTSEN, AND JAMES H. GRAHAM

Microbial Soil Amendments Do Little to Improve Citrus Tree Performance in Florida Soils

Page 134-139

The profitability of Florida citrus groves can be limited by poor soil conditions, including low nutrient and low water-holding capacity. There are many advertised soil amendments that claim to “condition” unproductive soils by improv­ing the balance of beneficial microbes even though there is no known research demonstrating the effectiveness and profitability of these products on citrus. We tested four commercially available microbial-based liquid soil amendment products that have been recommended by their manufacturers to be beneficial for citrus. In three repeated greenhouse studies, products were applied at recommended and higher rates to seedlings of Carrizo citrange grown in pots of native Candler sandy soil. In Experiment I, total plant growth tended to increase in response to amendments of two of the products (B, C), but growth responses to increased rates of B and C were not conclusive. Nitrogen leaching and leaf N responses were not remarkable. The other two products (A, D) had no effect on seedling growth or N budgets. Greenhouse experiments were repeated using B and C at high or low nutrition, but seedling growth and mineral nu­trient status were little affected. Nonetheless, products B and C were tested in three field-scale experiments at three locations (Southern flatwoods, Indian River, and central Ridge). The two products were applied at recommended rates with or without biosolids (sludge) to provide additional soil organic matter (SOM) microbial substrate. During 3 years of repeated applications and monitoring, the microbial products did not consistently affect any measured parameter in the soil or citrus crop. Soil measurements included SOM, pH, CEC, P, K, Ca, Mg, Fe, Cu, microbial respiration, PWP, and soil Phytophthora populations. Leaf analyses included color (SPAD), N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B. Tree canopy heights and volumes were measured, and fruit quality was expressed as fruit size, percentage juice, brix, acid, and ratio. Fruit yield could not be rigorously assessed because in 2 years the harvest was damaged by hurricanes, and one experiment was destroyed due to the canker eradication rule in Florida. Based on greenhouse and field studies, these microbial-based liquid soil amendment products were of little or no benefit. The additional cost and labor of incorporating these products into Florida citrus production programs could not be justified.
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WILLIAM S. CASTLE AND JAMES C. BALDWIN

Rootstocks Affect the 17-Year Survival and Performance of ‘Valencia’ Trees Grown in Immokalee

Page 140-144

A non-replicated planting of ‘Valencia’ orange [Citrus sinensis (L.) Osb.] trees on 19 rootstocks was estab­lished near Immokalee in 1991 to evaluate tree performance on a scale approximating commercial conditions. Trees on various standard or new rootstocks ranging from citranges [C. sinensis x Poncirus trifoliata (L.) Raf.] and citrumelos (C. paradisi Macf. x P. trifoliata) to Cleopatra, Sun Chu Sha, and Changsha mandarins (C. reticulata Blanco) were grown in a commercial nursery. Individual beds of 98 trees on one rootstock were planted at 14 × 22 ft (4.3 × 6.7 m; 141 trees/acre (348 trees/ha) in a commercial grove. The soil is mainly Malabar fine sand. Soil pH values were above 8 in places near the edges of the site where calcareous soil from nearby ditches was used to form beds; elsewhere in the site, soil pH averaged 7.8. Tree survival was above 90% except for those on rough lemon (C. jambhiri Lush.) and Cleopatra mandarin that lost 20% to 30% of the trees to blight and the complete loss of trees on sour orange (C. auran­tium L.) to tristeza virus. Trees on most rootstocks were about 12 to 13 ft (3.8 m) tall at age 9 years; those on Cleopatra mandarin and F80-5 citrumelo were the tallest at 14.5 ft (4.4 m) and those on Swingle citrumelo were 10.7 ft (3.3 m). The highest cumulative yields across six seasons came from trees on Carrizo and Benton citranges (14 to 15 [90 lb = 41 kg] boxes/tree); the lowest yield came from trees on Cleopatra mandarin (9.5 boxes). From juice quality data obtained in five seasons, the highest pound-solids/box values were from trees on Carrizo, Benton, and Rusk citranges. Thus, ‘Valencia’ trees on several new rootstocks, F80-14, Benton, several numbered citrumelos and on Sun Chu Sha, have the potential to exceed the performance of those on standard commercial rootstocks.
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WILLIAM S. CASTLE AND JAMES C. BALDWIN

Tree Survival, Growth, and Juice Quality of Early-season Sweet Orange Selections on Eight Rootstocks in Immokalee

Page 145-147

Eight early-maturing sweet orange selections that had been previously evaluated in a formal trial, includ­ing two blood oranges, and ‘Earlygold’, ‘Itaborai’, and ‘Ruby’, were planted in a commercial grove in 1995 south of Immokalee. The unreplicated planting was designed to observe performance of these selections on a commercial scale. It consisted of typical double-row beds planted at 10 × 24 ft with trees of one scion per bed divided among eight rootstocks. There were 80–120 trees/bed. After 9 years, the order of tree height across all scions was greatest on Smooth Flat Seville (14.5 ft; 4.4 m) > Goutou > Kinkoji > Benton citrange > Kuharske citrange > Carrizo citrange > Swingle citrumelo > C-35 citrange (11 ft; 3.4 m ). Yield was not measured in the planting, but occasional observation indicated that the trees on each rootstock were cropping at commercially acceptable levels. Using trees on Swingle citrumelo rootstock, juice quality was tracked over four seasons for ‘Earlygold’, ‘Itaborai’, and ’Ruby’ and compared with ‘Hamlin’ fruit collected from a nearby grove. Brix-acid ratios were about 20 by December. Juice color numbers of the three new selections usually exceeded that of ‘Hamlin’ by 1.5–2.0 points by mid-November. Pounds-solids/box were low by industry standards, about 5 pounds/box between mid-November and mid-December, with little difference among all scions. The good tree survival and growth on Smooth Flat Seville and Kinkoji suggested that they were among the most suitable for the site. Trees on C-35 citrange grew well on Wabasso fine sand soil, were relatively smaller in size, but appeared to crop well for their size.
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RANDALL P. NIEDZ

In Vitro Germination of Citrus Seed

Page 148-151

Seedlings germinated in vitro are commonly used as a source of explants for Agrobacterium-mediated transformation of citrus. Seed and seed treatments that result in rapid, uniform, and high percentage of germination are preferred. A number of seed treatments, including peeling, aeration, presoaking procedures, prehumidification, and sterilization procedures, were used on Citrus sinensis ‘Hamlin’ seed. Germination curves were produced and percentage, rate, and uniformity for each treatment combination were estimated. Results showed that seedcoat removal and sowing peeled seed on the surface of the agar medium substantially improves germination, and combining treatments provides ad­ditional improvements to germination.
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DENISE D. THOMAS AND NORMAN C. LEPPLA

The Likelihood and Consequences of Introduction of the Spherical Mealybug, Nipaecoccus viridis (Newstead), into Florida, and Its Potential Effect on Citrus Production

Page 152-154

The spherical mealybug, Nipaecoccus viridis (Newstead), is polyphagous and rapidly builds large populations due to its high fecundity and multiple, overlapping generations. It infests several economically important crops, including citrus, and reduces plant vigor, deforms fruit, induces leaf chlorosis, and promotes the growth of sooty mold. Although the spherical mealybug has not yet become established in the continental U.S., it has been intercepted 31 times at ports of entry. The likelihood of its introduction depends on the types and quantities of plants or plant products being imported into the United States and also on actions taken to intercept or rapidly eradicate adventive populations. Since the cli­mate in Florida is conducive to its development, N. viridis ultimately could become established and adversely impact citrus production and export. Nipaecoccus viridis has caused significant losses to citrus producers in other countries and, therefore, has become a regulated pest. Biological control has been the most successful method for managing the spherical mealybug and postharvest phytosanitary treatments could potentially be adapted to clean infested fruit.
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ED STOVER, WILLIAM S. CASTLE, AND PETER SPYKE

The Citrus Grove of the Future and Its Implications for Huanglongbing Management

Page 155-159

Revolutionary changes face Florida’s citrus industry as huanglongbing (greening) becomes widespread. Changing economic realities have encouraged many tree fruit industries to modify planting density, tree architecture, train­ing and production systems. More trees/acre translate into earlier bearing and less yield disruption as trees die, but with greater establishment costs per acre. A model for citrus production, which may permit profitable production in Florida using huanglongbing susceptible material, has been called an Advanced Production System combined with Open Hydroponic System. These practices have been adopted in a number of citrus producing countries, but need to be evaluated and adapted to Florida conditions. Practices that facilitate early cropping and fruit quality are critical to high density orchard profitability. Control of water and nutrients to manage tree development, girdling, use of plant growth regulators, larger planting stock, and tree supports may maximize early yields and help contain canopy volume. In the more distant future, genetic improvement solutions may contribute additional tools. The purpose of this paper is to stimulate discussion, facilitate assembly of diverse useful ideas in facing this challenge, and coordinate efforts within Florida to get a critical mass of production and economic data as quickly as possible.
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BOB EBEL AND JACKIE BURNS

Incorporation of Air Temperature into a Model That Predicts Loosening of Sweet Oranges by the Abscission Agent CMNP

Page 160-163

CMNP (5-chloro-3-methyl-4-nitro-1H-pyrazole) is an abscission agent that is in the process of being labeled as an aid for mechanical harvesting. A mathematical model that incorporates the most important factors affecting CMNP efficacy may be a useful tool for mechanical harvesting companies and growers to schedule abscission sprays and har­vests. Previous research has demonstrated that two of the most important factors include CMNP concentration and temperature. Using data from previous research, we developed a model using concentration and air temperature and applied it to 18 treatments from 5 studies that included 10 treatments for ‘Hamlin’ and 8 treatments for ‘Valencia’. Inputs into the model included CMNP concentration, hourly air temperature from time of application to harvest, and fruit detachment force (FDF) at time of application. The model calculated a predicted FDF at time of harvest, which was compared to actual FDF. The average FDF for the 18 treatments at time of application was 92 N. The average FDF at harvest was 51 N and the average predicted FDF was 58 N. Thus, the difference between actual and predicted FDF was about 13%. However, there was considerable variation among treatments, with the range in difference between actual and predicted FDF from –40 to 57 N. There was no difference between cultivars in predictability of the model. Factors causing this high variation between predicted and actual FDF at harvest will need to be included in the model before it will be commercial viable.
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BIELINSKI M. SANTOS

Evaluation of Nitrogen Rates and Irrigation Programs for Tomato Production in West Central Florida

Page 164-166

Two field studies were conducted to compare N rates by irrigation programs and their effects on tomato (Solanum lycopersicum L.) growth and yields. Twelve treatments resulted from combinations of irrigation and N fertilization programs. Irrigation programs were seepage irrigation at a water volume of 14 acre-inch/acre/season; seepage plus drip irrigation at a volume of 14 and 14 acre-inch/acre/season, respectively; and drip irrigation at a volume of 14 acre-inch/acre/season. N fertilization programs consisted of variations of preplant and drip-applied N at rates of 200, 250, and 300 lb/acre. Within the irrigation programs, the highest NO3-N petiole concentration was found in plots treated with a drip irrigation rate of 14 acre-inch/acre/season (448 ppm). For N rates, NO3-N petiole concentrations increased linearly with N rates and the highest values occurred with 300 lb/acre of N (435 ppm). Tomato marketable yield was the lowest (12.0 ton/acre) with the combination of seepage irrigation (14 acre-inch/acre/season) and with the preplant application of 200 lb/acre of N. All other irrigation by N fertilization combinations resulted on total marketable yields ranging between 19.4 and 25.9 ton/acre. These results indicated that in those systems where drip irrigation was used alone or in combination with seepage irrigation, a N rate of 200 lb/acre (bed centers 6 ft apart) might suffice for tomato production. In contrast, when only seepage irrigation was utilized at a rate of 14 acre-inch/acre/season, this N rate needs to be increased to 250 lb/acre.
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XIN ZHAO, JEREMY D. EDWARDS, BYUNG-HO KANG, ERIC H. SIMONNE, KAREN E. KOCH, ROBERT C. HOCHMUTH, STEPHEN M. OLSON, AND JOHN W. SCOTT

Plant Tumor Development on Tomato Derived from Lycopersicon hirsutum

Page 167-169

Nonpathogenic tumor (“Intumescence” or “Oedema”) is a physiological disorder that may develop on tomato (Ly­cospericon esculentum) leaves. Although genotype and water congestion resulting from the imbalance between plant water use and uptake have been considered as the primary cause of the blister-like symptoms, initiation and process of the tumorous growth remains unclear. A wild tomato species Lycopersicon hirsutum is known for its susceptibility to intumescence formation, particularly in greenhouse. In a recent greenhouse study of grafted tomatoes, the rootstock ‘Maxifort’ (a hybrid derived from L. hirsutum) showed marked symptom of foliar oedema, indicating the possibility of genetic inheritance of intumescences. Tomato ‘Florida-47’ did not exhibit any tumorous growth in either non-grafted treatment or grafted treatment with ‘Maxifort’ as rootstock. The incidence of oedema on ‘Maxifort’ was further evalu­ated when it was grafted onto the unsusceptible ‘Florida-47’. Replacing the roots of ‘Maxifort’ with that from an unsus­ceptible tomato variety did not alter the overall susceptibility of ‘Maxifort’ to intumescences as the injury was present in all the grafted ‘Maxifort’ plants. Internal morphology of oedema-afflicted leaves of ‘Maxifort’ revealed evident cell enlargement, while the involvement of cell division in intumescence development needs to be further determined.
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DANIELLE D. TREADWELL, AMY H. SIMONNE, THABILE P. NKAMBULE, ROBERT C. HOCHMUTH, WANDA L. LAUGHLIN, TERESA OLCZYK, CORSTIANA PEAVY, AND CATHERINE J. ROGERS

Yield, Chemical Composition, and Eating Quality of Heirloom Tomatoes Grown in the Subtropical Climate of Florida

Page 170-174

Florida small farm growers and producers are interested in strategies that can differentiate their operation and prod­ucts from the competition and heirloom tomato (Solanum lycoperscium L.) varieties have potential for adoption by small farm producers in Florida. Marketable yield, chemical compositions [vitamin C, pH, total soluble solid (TSS), titratable acidity (TTA)], and eating quality (semi-trained panelist, n = 38) of six tomato cultivars ( ‘Arkansas Traveler’, ‘Brown Berry’, ‘Cream Sausage’, ‘Jaune Flamme’, ‘Nyagous’, ‘Mortgage Lifter’) of field and shade-grown heirloom tomatoes were evaluated during Spring 2007 at the North Florida Research and Education Center–Suwannee Valley (NFREC-SV), in Live Oak, FL. Marketable yield of cultivars ranged from 0.9 to 4.57 kg/plant. The tomato cultivar with the highest vitamin C content was ‘Brown Berry’ (26.18 mg/100g) and the lowest vitamin C content was in ‘Nyagous’ (13.40 mg/100g). The sensory evaluation was conducted only on varieties with high marketable yield from Live Oak (‘Brown Berry’, ‘Cream Sausage’, and ‘Jaune Flamme’). Age and gender of the taste panel did not affect the rating score of the sample (P > 0.05) but samples were significantly different (P < 0.0008). There was no specific trend that indicated a flavor preference for shade-grown tomato compared to field-grown tomato. A similar trial was completed during Fall 2007 at NFREC-SV and Winter 2007–08 at the Tropical Research and Education Center in Homestead, FL. Those studies evaluated yield and fruit quality of six cultivars considered “red slicers” produced hydroponically in open shade houses. Several heirloom cultivars tested in this trial were suitable for direct market, but none would be suitable for large-scale commercial production.
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BIELINSKI M. SANTOS AND JOHN W. SCOTT

Response of ‘Fla. 8153’ Tomato to Nitrogen Fertilization Programs and In-row Distances

Page 175-177

Two field studies were conducted to determine the most appropriate N fertilization program and in-row distances for ‘Fla. 8153’ tomato (Solanum lycopersicum L.). Six treatments resulted from the combination of three N fertilization programs and two in-row distances. Total N rates (204, 239, and 274 lb/acre/season) were the result of the combination of 50 lb/acre of N during prebedding plus each of the following drip-applied N rates: a) 1.5, 1.5, and 2.0 lb/acre/day during weeks 1 to 2, 3 to 4, and 5 to 12, respectively (154 lb/acre/season); b) 1.5, 2.0, and 2.5 lb/acre/day during weeks 1 to 2, 3 to 4, and 5 to 12, respectively (189 lb/acre/season); and c) 1.5, 2.5, and 3.0 lb/acre/day during weeks 1 to 2, 3 to 4, and 5 to 12, respectively (224 lb/acre/season). In-row distances and N fertilization programs had significant effects on early and total marketable yields of ‘Fla. 8153’ tomato, but the interaction between in-row distances and N fertilization programs was not significant. The results indicated that application of 50 lb/acre of N preplant plus 224 lb/acre through the drip lines (274 lb/acre/season of N) could improve early and total yields of ‘Fla. 8153’ in comparison with the other two tested programs (204 and 239 lb/acre/season of N). Therefore, it appears that the recommended rate of 200 lb/acre/season might not be enough to maximize ‘Fla. 8153’ yields. At the same time, this cultivar produced its largest yields per area when planted at 18 inches between plants in comparison with 24 inches, regardless of N fertilization rates.
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ERIC SIMONNE, REVA DATAR, AMY SIMONNE, ROBERT HOCHMUTH, AND APARNA GAZULA

Sensory Evaluation of Red and Yellow Grape Tomato Varieties

Page 178-182

Grape tomatoes (Solanum lycopersicon L. var. cerasiform) have recently gained popularity because they are convenient to eat, sweet and flavorful, and are a recognized as a good source of vitamins C, and A, and lycopene. Because of the limited seed availability of the standard variety ‘Santa’, the objective of this study was to identify suitable replacement varieties for three segments of the grape tomato industry. The first taste test included commercial red varieties (‘Sug­ary’, ‘Red Grape’, ‘St. Nick’, ‘Santa’, ‘Sweet Olive’, and ‘Tami G’), the second one included red varieties suitable for small farm production (‘Cupid’, ‘Sugary’, ‘Sweet Hearts’, ‘Jelly Bean’, ‘Jolly Elf’, and ‘Santa’), and the third one included yellow varieties (‘Gold Nugget’, ‘Golden Sweet’, ‘Honey Bunch’, and ‘Sun Gold’). All varieties but ‘Santa’ were grown at the North Florida Research and Education Center–Suwannee Valley. A 33-member panel rated the varieties for sweetness, acidity, flavor, and overall preference on a 90-mm unstructured line. Significant differences were found for most attributes, but variability was high (CV ranging from 47% to 61%). Based on an overall rank sum index, ‘Red Grape’, ‘Sugary’ and ‘Cupid’, and ‘Sun Gold’ were rated highest varieties in each category. Surpris­ingly, the store-bought ‘Santa’ was among the least preferred red varieties. Together with consumer preference, factors such as market needs, seed availability, growth habit, and disease resistance/tolerance should also be considered when selecting a grape tomato variety.
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CHRISTINE M. WORTHINGTON AND CHAD M. HUTCHINSON

Fate and Movement of Nitrogen and Phosphorus in Deep Creek in the Lower St. Johns River Basis of Northeast Florida

Page 183-186

According to the St. Johns River Water Management District, approximately 36% of the pollutant load entering the lower St. Johns River basin is related to human activities. Deep Creek, a tributary in the lower St. Johns River basin, drains approximately 4,000 ha of irrigated cropland in and around Hastings through a system of tail water and drainage canals into Deep Creek. Objectives of this project were to measure water quality and aquatic plant density effects in Deep Creek. Water samples collected were analyzed for nitrate-nitrogen, ammonium-nitrogen, potassium and total phosphorus. Blue-green algae, chlorophyll a, dissolved oxygen, pH, specifi c conductivity and water temperature were measured at 23 sample sites on a weekly schedule in Oct. 2007. Total phosphorus concentration within Deep Creek at the 1st, 13th, and 15th sample locations were significantly higher compared with all other sample sites at 896.4, 930.7, and 896.9 μg·L–1, respectively. A significant correlation between total phosphorus and chlorophyll a was observed.  Chlorophyll a increased as total phosphorus increased. Alternatively, a significant inverse relationship was observed as nitrate-nitrogen concentrations decreased, chlorophyll a increased. Continued data collection will further support Best Management Practices strategies for the Tri-County Agricultural Area of Northeast Florida.
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ZHIWEI CHEN AND CHAD M. HUTCHINSON

Evaluation of Alternative Fertilizer Programs in Seepage Irrigated Potato Production

Page 187-190

The influence of controlled release fertilizer programs and application timing on ‘Atlantic’ (Solanum tuberosum L.) production, tuber quality, and water quality were evaluated. Treatments were arranged in a randomized complete block with four replications. Application timing was at fumigation (21 days prior to planting), planting, at hilling (30 days after planting), and a combination of timings. Fertilizer treatments were no N, ammonium nitrate (N at 224 and 280 kg·ha–1), polymer sulfur coated urea, polymer coated urea, and three liquid urea formaldehyde formulations. Controlled release fertilizer N rate was 196 kg·ha–1. Plants fertilized with the ammonium nitrate (N at 224 kg·ha–1) treatment produced the highest total and marketable yield (39.3 and 34.1 MT·ha–1) significantly higher than with the urea formaldehyde treatments. Total and marketable yields from plants fertilized with polymer sulfur coated urea and polymer coated urea treatments were similar to the ammonium nitrate treatments when the majority of N fertilizer was applied at or before planting. No significant difference was found between fertilizer treatments for tuber quality. The 2007 season was relatively dry with limited N leaching pressure, resulting in few observed differences between treatments for nitrate concentration in the root zone or perched water table over the season.
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A.R. RAFIE AND CHRIS MULLINS

Greenhouse Bitter Melon Production in Southern Virginia

Page 191-193

Bitter melon (Momordica charantia) is a member of the Cucurbitaceae (gourd) family, a relative of squash, watermelon, and cucumber. It is considered an important vegetable for the Asian and Indian populations living in the United States. Bitter melon is usually grown in the field during the summer months; however, the price of bitter melon is consider­ably higher from December to May when it is imported from other countries. No information is available about bitter melon production in a greenhouse setting and whether higher market prices justify the higher production costs. In Dec. 2007, a study was conducted with two different trellis systems at the Virginia State University greenhouse facility to study this possibility. The production per plant for a 6-month harvest was 62 and 42 lbs for vertical and horizontal trellis systems, respectively.
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DANIEL J. CANTLIFFE, JAMES E. WEBB, JOHN J. VANSICKLE, AND NICOLE L. SHAW

Increased Net Profits Result from Greenhouse-grown Colored Pepper Compared to Field Production in Florida

Page 194-200

The United States is one of few countries where the majority of bell peppers (Capsicum annuum L.) produced are green colored and grown on raised beds with mulch and drip irrigation. Outside the U.S., most peppers are grown in greenhouses and harvested as mature, colored peppers that receive a premium value at market. Florida bell pepper producers are in direct competition with Mexico, Israel, and Spain due to overlapping seasons in the winter months, while greenhouse producers in Canada and Holland are able to enter the U.S. market during the spring, summer, and early fall. Greenhouse vegetable production could be one alternative to field production of bell peppers for Florida fresh market vegetable growers. The objective of this study was to determine the costs and benefits associated with greenhouse pepper production. Through the use of software (SIMETAR©), a budget analysis model was created for greenhouse bell pepper production. Although greenhouse production requires a significantly larger capital investment compared to field production, potential profits from growing colored peppers have been determined to be as much as four times greater in greenhouse production than from field production ($15,166/acre compared to $3,289/acre, re­spectively). Greenhouse production may allow Florida growers searching for alternatives to field production a viable alternative to stay competitive in the U.S. fresh vegetable market.
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TERESA P. SALAME, BIELINSKI M. SANTOS, CRAIG K. CHANDLER, AND STEVEN A. SARGENT

Horticultural Potential of Producing Florida Strawberry Cultivars under High Tunnels

Page 201-203

Protected strawberry (Fragaria ×ananassa Duch.) production is widely used in Europe and other parts of the world. However, in California and Florida open-field production remains the main production system. Strawberry production in high tunnels could potentially increase yield, improve fruit quality, promote early ripening, reduce pest incidence and rain damage. If adopted in Florida, this technology would open new opportunities for long-term changes on strawberry production practices and an eventual increase in grower profits. The objective of this study was to compare growth, fruit earliness and yield of strawberry cultivars grown under tunnels and in open fields. The cultivars ‘Strawberry Festival’, ‘Winter Dawn’ and ‘Florida Elyana’ were tested inside of 16-ft high tunnels and in open fields during the 2007–08 season. Results showed that total marketable yields of ‘Strawberry Festival’, ‘Winter Dawn’, and ‘Florida Elyana’ increased by 39%, 87%, and 85%, respectively, in tunnels, compared with the open fields in the 2007–08 season when freeze temperatures occurred.
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KENNETH D. SHULER, PEI-ANN N. SHULER, STEPHEN J. NIE, AND DEANNA V. SHULER

Growing and Marketing Basil at Local Green Markets in Southeast Florida

Page 204-207

Sweet basil (Ocimum basilicum L.) was first grown in 2002 in the 0.38-acre backyard market garden of Stephen’s Produce. It was one of 30 crops being grown to help supply local green markets with a weekend supply of “garden fresh” produce. Planting schedules, growing and harvesting methods, yields, and sales figures will be discussed. For the 2003–04 season, 18 plantings of basil were made. Basil was sold at all of the 32 weekends for the sales season, which began 19 Oct. and concluded 22 May. Stems were cut, bunched, and banded the day before sales. Bunches were either stored in a cooler with ice or stood upright in a bucket or bin with water. Bunches of 5–10 stems were generally sold for $1.00 to $2.00 each. Plants were allowed to regrow for multiple harvests at 3- to 4-week intervals. In 2003–04, an average of 50 bunches of basil were sold each week.
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DANIEL J. CANTLIFFE, JAMES E. WEBB, JOHN J. VANSICKLE, AND NICOLE L. SHAW

Potential Profits from Greenhouse-grown Organic Strawberries Are Greater than Conventional Greenhouse or Field-grown Strawberries in Florida

Page 208-213

In Florida, 7,100 acres of fresh strawberries (Fragaria ×ananassa Duch.) were planted in fields during the 2003–04 growing season using polyethylene mulch raised beds and drip irrigation. Florida is the second largest fresh market strawberry-producing state behind California. Because Florida enters the market prior to California during the winter months, Florida strawberry value per pound exceeds that of California ($1.10/lb compared to $0.62/lb, respectively). Florida strawberry growers are faced with many challenging obstacles such as the loss of methyl bromide, urbaniza­tion, weather, water restrictions, pests, and foreign competition. Many of these challenges are removed with the use of a protected structure such as a greenhouse. The objective of this research was to create a model determining the feasibility of greenhouse production of strawberries, grown both conventionally and organically, as an economical alternative for Florida strawberry growers competing in a global market. Although greenhouse production requires a significantly larger capital investment (total costs organic: $158,076/acre; non-organic: $168,951/acre) compared to field production ($25,602/acre), potential profits of greenhouse-grown organic strawberries were as much as 9.5 times greater than field production ($22,316/acre compared to $2,419/acre, respectively). Conventionally-grown greenhouse strawberries profits ($3,855/acre) were 1.5 times greater than field production. These findings are significant for Florida growers searching for alternatives to field production.
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KENNETH D. SHULER, PEI-ANN N. SHULER, STEPHEN J. NIE, AND DEANNA V. SHULER

Growing and Marketing Collards and Kale at Local Green Markets in Southeast Florida

Page 214-218

Collards (Brassica oleracea var. viridis L.) were first grown in 2002 and kale (Brassica oleracea var. sabellica L.) in 2004 in the 0.38-acre backyard market garden of Stephen’s Produce. It was one of 30 crops being grown to help supply local green markets with a weekend supply of “garden fresh” produce. Planting schedules, growing and harvesting methods, yields, and sales figures will be discussed. For the 2007–08 season, five plantings of collards and eight plantings of kale were made. Collards and kale were sold at all but one of the 28 weekends for the sales season, which began 20 Oct. and concluded 27 Apr. Young collard and kale leaves were broken off plants, bundled, banded, and stored in a cooler with ice the day before sales. Bunches of 18–30 collard leaves were generally sold for $2.00 to $3.00 each. Bunches of 16–22 kale leaves were generally sold for $1.50 to $2.00 each. In 2002–03, an average of 15 bunches of collard greens were sold each week. In 2004–05, an average of 21 bunches of kale were sold each week.
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RAMU GOVINDASAMY, RICHARD VANVRANKEN, WILLIAM SCIARAPPA, ALBERT AYENI, VENKATA S. PUDURI, KIM PAPPAS, JAMES E. SIMON, FRANK MANGAN, MARY LAMBERTS, AND GENE MCAVOY

Ethnic Crop Opportunities for Growers on the East Coast: A Demand Assessment

Page 219-221

The rapid change in the ethnic population in the eastern coastal USA has consequences in the food and vegetable markets. As demographic profiles change, growers may wish to change their focus of food and vegetable production to capture the changes in demand. In this paper the scope of the expansion of ethnic crops in the eastern coastal USA by the growers from an economic perspective based on demand revealed by a survey is examined. It gives us an idea and understanding of the demand for ethnic crops by four ethnic groups: Chinese, Asian Indians, Mexicans, and Hispanics. In this report the differences and similarities with respect to crop selection and spending patterns are summarized. Results reported have important implications for the development of ethnic crop production locally.
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DANIEL J. CANTLIFFE, JAMES E. WEBB, JOHN J. VANSICKLE, AND NICOLE L. SHAW

The Economic Feasibility of Greenhouse-grown Cucumbers as an Alternative to Field Production in North-central Florida

Page 222-227

Florida is the leading producer of fresh-market cucumbers (Cucumis sativus L.) in the United States and accounts for 24% of the total value of the U.S. fresh-market industry. Florida cucumbers are generally produced on raised beds covered with polyethylene mulch and fumigated. With the loss of methyl bromide, Florida cucumber producers as with other vegetable growers in Florida, are searching for alternatives. The objective of this research was to gather pertinent information from public, private, and research sources to create an economic feasibility model that compares the costs and benefits associated with field-grown slicing cucumbers and the production of European-type greenhouse cucumber in Florida. Though greenhouse production requires a significantly larger capital investment (total cost: $391,922/acre) compared to field production (total costs: $5,620/acre), potential profits have been determined to be as much as 1,206 times greater for greenhouse produced cucumbers than in the field (profits: $72,775 compared to $60/acre, respectively). Greenhouses provide opportunities for Florida growers faced with urbanization, water restrictions, and the loss of methyl bromide, as well as minimize risks associated with weather, and pests and disease pressures. This study will demonstrate that it is not only economically feasible to produce cucumbers in a greenhouse setting, but the potential profits are significantly greater for greenhouse-grown cucumbers compared to field-grown cucumbers in Florida.
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ROBERT KLUSON, ROY BECKFORD, AND ROBERT HALMAN

The South West Florida Small Farmer Network: A Participatory and Regional Approach to Diversified Horticultural Production Extension

Page 228-229

The South West Florida Small Farmers Network (SWFSFN) is one of the new farmer-to-farmer networks supported by the UF/IFAS/FAMU Small Farms and Alternative Enterprises Program. These working groups have been devel­oped to meet the unique education needs of Florida small farmers. For example, the successful models for sustainable horticultural small farming in Florida and across the nation include highly diversified agro ecosystems. The teaching of crop and enterprise diversification provides benefits for sustained production (Gliessman, 2006), marketing (Bandele, 1999). and lowering economic risk (USDA/RMA, 2008). These agro ecosystems require increased knowledge of different crops, enterprises, and marketing compared to past single or limited commodity-based operations. This paper describes the approach and activities implemented by the SWFSFN to provide this information, research, and support.
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NICOLE L. SHAW, DANIEL J. CANTLIFFE, CHAD M. HUTCHINSON, STEVEN A. SARGENT, AND DAVID DINKINS

Greenhouse Production of the Famous St. Augustine Hot Pepper, the Datil (Capsicum chinense var.)

Page 230-233

Datil pepper (Capsicum chinense var.) is well known throughout St. Augustine, FL where it has been cultivated since the 1700s. Liked for their unique sweet-hot flavor, datil peppers are used for cooking, hot sauces, relishes, and other condiments. Mainly grown in backyard gardens, numbers of plants grown for commercial purposes are unknown. Seeds are not commercially available, but found via the internet, festivals, Master Gardeners, or as family heirlooms. Four selections were cultivated under passively ventilated greenhouse conditions in Citra, FL. Seeds were sown 26 Jan. 2006 and transplanted into 11-L pots filled with pine bark on 15 Mar. Plants were grown at 2.2 plants/m2 until 2 Aug. when plants were cut back to 30-cm height and re-spaced at 0.5 plants/m2. Plants were harvested 6 times from 8 June to 31 July at 2.2 plants/m2 and 4 times at 0.5 plants/m2 from 26 Oct. 2006 to 3 Jan. 2007. Marketable fruit number/m2 was similar between densities, but significantly different between selections and ranged from 234 to 392 fruit/m2. Interac­tions between plant density and selection for marketable fruit weight/m2 and cull number/m2 were significant. ‘Super Datil’ produced nearly twice the fruit weight at 0.5 than at 2.2 plants/m2; other selections were not affected by plant density (yields ranged from 0.8 to 1.4 kg/m2). ‘Super Datil’ was determined not to be a true datil pepper. A selection named ‘Norm’ (handed down through several family generations), was included on 17 May 2006 and harvested three times (4, 26 Oct., and 13 Nov. 2006). ‘Norm’ produced a yield nearly three times greater than the other four selections in the trial at 998 fruit/m2 and 2.7 kg·m–2.
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ROMY KRUEGER, KOON-HUI WANG, ROBERT MCSORLEY, AND RAYMOND N. GALLAHER

Artificial and Natural Pollination of Sunn Hemp in Florida

Page 234-237

Sunn hemp (Crotalaria juncea L.) is considered an important cover crop, providing benefits in weed, disease, and pest suppression, and supplying N to the soil. While the demand for sunn hemp seeds is high, seed production of sunn hemp in mainland US has been limited. Over the duration of two seasons (2005–06), various treatments for enhancing pod and seed set were tested in three experiments in northern Florida. The main objective was to determine if the plant growth regulator ethephon could substantially improve pod and seed set. Other methods tested were manual removal of the flower petals and beating of the stem to stimulate self-pollination within an inflorescence. In most instances, all treatments produced similar amounts of pods and seeds compared to an untreated control. In a few cases, significant (P < 0.05) differences among treatments occurred in pod and seed production, but these were very limited. In one trial in 2005, a higher ethephon concentration (16.7 μL·m–2 a.i.) produced more pods than a lower concentration (8.3 μL·m–2 a.i.), but did not produce more pods than the untreated control. Results suggest that native pollinators were competitive with the artificial pollination methods examined in this experiment.
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EUGENE J. MCAVOY AND WILLIAM M. STALL

Tolerance of Fresh Market Dill, Parsley, and Cilantro to Potential Herbicides in Florida

Page 238-240

Parsley (Petroselinum crispum Mill.), cilantro (Coriandrum sativum L.), and dill (Anethum graviolens L.) are grown on minor acreages in Florida, but are a major part of many fresh market mixed-load shipments to northern markets. Registered herbicides on these three crops are few. Trials were established in Hendry County, FL, at C&B Farms in Dec. 2006 and Feb. 2007 to evaluate several herbicides on dill, parsley, and cilantro grown on mineral soils. Treat­ments consisted of PRE applications of metolachlor (Dual Magnum), dimethenamid (Outlook), and pendimethalin (Prowl H2O). In 2006, prometryne (Caparol) was applied at three rates PRE. In 2007, prometryne was applied two rates PRE and POST. Linuron (Lorox) was applied at one rate PRE, one rate POST, and two rates PRE plus POST. There were differences in tolerance among the crops to a herbicide and differences in tolerances to the herbicides of the crops. The crops were least tolerant to dimethenamid applied PRE. No stand reduction or stunting was seen in the three crops in the metolachlor and Prowl H2O treatments. Some problems were observed with other materials especially at higher rates.
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JAMES F. PRICE AND CURTIS A. NAGLE

Comparative Activity of Registered and Experimental Miticides to Control Twospotted Spider Mite [Tetranychus urticae Koch (Acari: Tetranychidae)] in Plant City Area Strawberry

Page 241-243

Twospotted spider mite (Tetranychus urticae Koch) management in strawberry (Fragaria ×ananassa Duchesne) was evaluated in two field experiments during 2007 that measured effectiveness of various miticides, a non-ionic surfactant, and their frequency of application. Miticides evaluated included two formulations of abamectin [abamectin A (Agri-Mek® 0.15 EC) and abamectin B (Zoro® 0.15 EC)], and single formulations of bifenazate, essential oil of Chenopodium ambrosioides L., hexythiazox, and spiromesifen. All of the miticides provided significant reductions in motile form spider mites. Three weeks after initial application of treatments, the most effective reductions in motile forms occurred when abamectin, bifenazate, hexythiazox, or spiromesifen were used. Most miticides reduced numbers of mite eggs; however, ovicidal hexythiazox did not because treated eggs failed to hatch.
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EUGENE J. MCAVOY AND WILLIAM M. STALL

Tomato, Pepper, and Watermelon Tolerance to EPTC Applied under Mulch in Florida

Page 244-245

For over 35 years, Florida tomato (Lycopersicum esculentum L.) growers have relied on methyl bromide for their soilborne pest, disease, and weed control problems. The use of methyl bromide as a soil fumigant is now being phased out under the Montreal Protocol. Yellow nutsedge (Cyperus esculentus L.) and purple nutsedge (Cyperus rotundus L.) are among the major weed control challenges in many tomato production systems. Since the leading alternative fumigants provide less than satisfactory control of nutsedge, Florida growers may have to consider the use of a preplant herbicide for control. EPTC (s-ethyl dipropylthiocarbamate) is an effective material that provides selective pre-emergent control of grasses, sedges, and many broadleaf weeds. Three years of small plot trials in Florida have shown that application of EPTC to the bed surface just prior to mulch application with a 14-day pre-transplant waiting period delivered excellent crop safety with very good nutsedge control. On-farm demonstration trials in Southwest Florida on tomato using EPTC applied to the bed and immediately covered with polyethylene fi lm also demonstrated excellent nutsedge control and had no apparent effect on the crop. Early indications are that EPTC may be an important tool in tomato weed management in the development of methyl bromide alternative strategies.
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TERESA E. SEIJO, CRAIG K. CHANDLER, JAMES C. MERTELY, CATALINA MOYER, AND NATALIA A. PERES

Resistance of Strawberry Cultivars and Advanced Selections to Anthracnose and Botrytis Fruit Rots

Page 246-248

Strawberry (Fragaria ×ananassa Duch.) cultivars and advanced selections were evaluated for resistance to anthracnose fruit rot (caused by Colletotrichum acutatum) and botrytis fruit rot (caused by Botrytis cinerea) in field trials in west-central Florida during the 2004–05, 2006–07, and 2007–08 seasons. Fruit were harvested twice weekly and anthracnose and botrytis fruit rot incidence were evaluated each season. The incidence of anthracnose fruit rot ranged from 1% to 10% in 2004–05, <1% to 9% in 2006–07, and 1% to 54% in 2007–08. For anthracnose, ‘Sweet Charlie’, ‘Ruby Gem’, ‘Florida Elyana’, and ‘Florida Radiance’ were the most resistant cultivars tested; ‘Strawberry Festival’ and advanced selection 99-117 were intermediate in susceptibility; and ‘Albion’, ‘Camarosa’, ‘Camino Real’, ‘Ventana’, ‘Candonga’, and ‘Treasure’ were susceptible/highly susceptible. The incidence of botrytis fruit rot ranged from 5% to 38% in 2004–05, 0.3% to 8% in 2006–07, and 1% to 6% in 2007–08. Assessment of cultivars for resistance to botrytis fruit rot was more difficult due to low disease incidence. However, ‘Camarosa’, ‘Florida Radiance’, ‘Florida Elyana’, and advanced selections 99-117 and 99-164 showed good levels of resistance, whereas ‘Camino Real’, ‘Ventana’, ‘Treasure’, ‘Candonga’, ‘Strawberry Festival’, and ‘Sweet Charlie’ were more susceptible.
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TERESIA W. NYOIKE AND OSCAR E. LIBURD

Application of Imidacloprid and Cultural Techniques for Management of Whiteflies in Cucurbits

Page 249-251

Living mulch, buckwheat Fagopyrum esculentum Moench, and ultraviolet reflective mulch in combination with Imida­cloprid (Admire 2F) significantly reduced Cucurbit leaf crumple virus, a whitefly-borne virus and its vector (B biotype of Bemisia tabaci Gennadius) in zucchini squash (Cucurbita pepo L.). Treatments evaluated included living mulch with and without imidacloprid) and ultraviolet reflective mulch with and without imidacloprid. Living and reflective mulches were compared with standard white mulch (control) in a completely randomized block design in Fall 2006 in Florida. Results indicated that plants growing within the white mulch had the highest number of whitefly immatures compared with all the other treatments. In November, plants were observed to show virus symptoms, which were identified to be caused by Cucurbit leaf crumple virus (CuLCrV). Plants growing within white mulch had the highest incidence of CuLCrV while the lowest incidence was observed in mulches with imidacloprid. Imidacloprid significantly reduced the number of whitefly immature populations in the zucchini squash leaves only when used with buckwheat mulch but not with reflective mulch.
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DAKSHINA R. SEAL

Effectiveness of Biological Insecticides in Controlling the Diamondback Moth (Lepidoptera: Plutellidae) Using Bacillus thuringiensis, Azadirachtin, and New Insecticides on Cabbage

Page 252-259

Diamondback moth, Plutella xylostella (L.), is the most destructive pest of cruciferous crops in the world. Various studies were conducted in 2007 and 2008 to control diamondback moth using Bacillus thuringiensis, azadirachin, and new insecticides. The B. thuringiensis-based product, VBC 60129, did not reduce diamondback moth populations. Bacillus thuringiensis, subsp. kurstaki, strain ABTS-351 (DiPel® DF) at 0.5 and 1.5 lb/acre signifi cantly controlled diamondback moth when applied weekly or biweekly. Application of B. thuringiensis at weekly intervals provided better control of diamondback moth than the application of same products at 2-week intervals. Azadirachtin 1.2% ME (Ecozin® plus, 8.0 oz/acre) signifi cantly reduced diamondback moth larvae. The premixed products, chlorantraniliprole + thiamethoxam (Voliam FlexiTM ) and chlorantraniliprole + lambda-cyhalothrin (Voliam XpressTM) at all experimental rates significantly reduced diamondback moth populations. Azadirachtin-based products were also effective in reducing diamondback moth.
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CELINE JOUQUAND, CRAIG CHANDLER, KEVIN GOODNER, AND ANNE PLOTTO

Optimization of Strawberry Volatile Sampling by Direct Gas Chromatography Olfactometry

Page 260-264

The aim of this work was to determine the most suitable sampling headspace technique for the study of strawberry (Fragaria ×ananassa Duch.) fruit aroma. The aromatic qualities of different headspace extracts of strawberry (‘Festi­val’) puree were evaluated using direct gas chromatography-olfactometry (D-GC-O), a technique that allows assessing global odor from solvent-free extracts without chromatographic separation. Two solid phase microextraction (SPME) extracts, with different types of fibers, polydimethylsiloxane/divinylbenzene (PDMS/DVB) and divinylbenzene/car­boxen/polydimethylsiloxane (DVB/CAR/PDMS), and two static headspace extracts, with different phase ratios (ratio of gas to sample phase volumes), were evaluated using D-GC-O. A similarity test with three panelists allowed comparison of the odor of these extracts to that of strawberry puree. The results indicated that SPME using a DVB/CAR/PDMS fiber generated the most representative odor, a “green” impression and a strong “fruity” note. A fruity note was also obtained with the 10-mL static headspace extracts, which exhibited a volatile concentration that was higher than that in the 20-mL headspace. When comparing the aroma profile of each extract, the DVB/CAR/PDMS extract showed the highest concentration of methyl butanoate and ethyl butanoate, two key compounds in strawberry aroma.
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ANNE PLOTTO, ELIZABETH A. BALDWIN, T. GREG MCCOLLUM, JAN A. NARCISO, AND MIKE IREY

Effect of Early Detection Huanglongbing on Juice Flavor and Chemistry

Page 265-269

When huanglongbing (HLB) was first discovered in Florida, trees with early symptoms of disease were harvested to determine whether there was any flavor difference between juice made from infected trees but with asymptomatic fruit, and fruit harvested from healthy trees. It is of interest to the processing industry to determine what affect fruit from trees of various stages of infection would have on processed orange juice quality. ‘Valencia’ oranges were harvested in 2006 from trees that tested positive for Liberibacter asiaticus, the presumed causal agent of HLB, in the early stages of disease development (HLB fruit), and compared to fruit from healthy trees (control). A consumer panel did not perceive differences for taste or smell between control and HLB juice in a triangle test. An experienced panel, however, did perceive that juice from HLB fruit was sweeter than juice from non-HLB fruit. Further tests were performed by using the “difference-from-control” test with filtered or unfiltered juice, to determine the effect of pulp on difference perception. When juice was filtered, panelists could perceive a difference by smell and by taste; when juice was served unfiltered they could only perceive a difference by taste. One of the descriptors that came up frequently for the HLB filtered juice for taste difference was again “sweeter.” Chemical analyses showed that the juice from HLB fruit was lower in acids and higher in acetaldehyde content and soluble solids-to-acid ratio than from juice from non-HLB fruit, which is in agreement with the “sweeter” perception. Methanol, 2-methyl propanol, and α-pinene were also higher in juice from HLB fruit. Differences in the remaining volatiles were due to the presence of pulp but not to the health status of the tree.
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ADRIAN D. BERRY AND STEVEN A. SARGENT

The Potential Use of a Microsensor to Measure Endogenous Oxygen Content in Fresh Fruit

Page 270-273

A pc-controlled, fiber-optic oxygen meter was tested to determine the potential of measuring endogenous oxygen levels in fresh fruits. Cucumber (Cucumis sativus L.) and tomato (Solanum lycopersicum L.) fruit were selected for this study. Endogenous oxygen level of cucumber fruit was measured using several methods; however, obtaining results without damaging the sensor was difficult due to the firm structure of the mesocarp tissue. Method 1 involved creating a small hole (perpendicular to the fruit surface), for sensor placement, by inserting a 23-gauge needle (0.6-mm diameter and 25-mm length) to a depth of 25 mm. Method 2 was developed to avoid damaging sensors, which involved creating a larger cavity for sensor placement by removing a 5-mm diameter, 34-mm length directly under the epidermis, starting at the blossom end. Oxygen content of cucumber fruit was approximately 19% when measured at 6-mm or 12-mm depth (using Method 1). Cucumber fruit treated with a commercial vegetable coating had lower oxygen content (11%) compared to untreated (18%) using Method 2. Endogenous oxygen level of tomato was also determined in locule and blossom-end tissues (10-mm depth). Fruit at pink and light red ripeness stages were measured initially and after 3 d at 24 °C. The oxygen level was lower in the locule (5%) than in the blossom end or columella tissue (15%). There was no difference in oxygen level for either ripeness stage. Real-time measurement of endogenous oxygen is feasible us­ing this microsensor, although its fragile construction requires precise positioning and use of soft-textured fruits and vegetables.
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JEANMARIE M. MITCHELL, DANIEL J. CANTLIFFE, HARRY J. KLEE, STEVEN A. SARGENT, PETER J. STOFFELLA, AND DENISE TIEMAN

Fruit Quality and Aroma Characteristics of a Specialty Red-fleshed Melon (Cucumis melo L.), ‘Red Moon’

Page 274-280

 ‘Red Moon’ is a red-fleshed melon (Cucumis melo L.) that is sold as a high quality fruit trademarked “Perfect Melon.” The purpose of this research was to determine whether ‘Red Moon’ fruit quality factors, including aroma volatiles would be altered by harvesting at different stages of fruit development (no-slip (NS), abscission layer development at stem (AL), full-slip (FS)) or by fruit storage (0, 5, or 10 days). The melons were grown in a passively-ventilated high-roof greenhouse in Florida. Data were recorded for days to harvest, fruit size, quality variables (soluble solids content, titratable acidity, pH, firmness), ethylene and respiration rates, and aroma volatiles. On S-0 (S-0), stage NS was firmest (46 N). All other fruit quality variables, ethylene and respiration rates were similar for all stages. After 5 days storage (S-5), overall firmness was decreased from S-0, however stage NS was firmest (17 N). Soluble solids con­tent (SSC) was higher at S-5 than S-0 for stages AL and FS. There were no differences among fruit maturity stages in other quality variables, ethylene or respiration rates at S-5. Following 10 days storage (S-10), all fruit quality variables were reduced compared to S-0 and S-5 treatments, regardless of fruit maturity. There were 15 volatile compounds found to be significant contributors to the aroma of ‘Red Moon’ at all stages. Volatiles were greatest at S-0 for fruit maturity stages AL and FS. Following S-5 and S-10, total identified volatiles were similar regardless of maturity stage. Overall, volatiles decreased over storage time from 0 to 10 days. ‘Red Moon’ melons had SSC of 11 °Brix regardless of stage of maturity harvested or duration of storage. The high SSC most likely attributes to their high quality status. To ensure highest fruit quality, it is recommended that ‘Red Moon’ melons be harvested at stages NS or AL for best firmness and quality.
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CAMILLE E. ESMEL, JOHN R. DUVAL, BIELINSKI M. SANTOS, STEVEN A. SARGENT, AND ERIC H. SIMONNE

Is Strawberry Fruit Firmness Associated with Tissue Ca Concentration?

Page 281-284

Several studies have focused on the improvement of strawberry (Fragaria ×ananassa Duch.) fruit firmness with additional calcium (Ca) applications. These studies found conflicting results for additions of Ca when it is applied as soil-applied gypsum or various foliar formulations. Because limited information exists on the association between fruit firmness and tissue Ca concentration in commercial strawberry cultivars, the objective of this study was to determine if leaf or fruit Ca concentration is a reliable predictor of fruit firmness. Leaf and fruit samples for Ca concentration and firm­ness measurements were determined in Feb. and Mar. 2004 on seven cultivars and correlations were conducted using Pearson’s correlation coefficient. Ca concentration and fruit firmness was significantly different among cultivars. Leaf Ca concentrations ranged between 8,390 (‘Camarosa’) and 11,986 (‘Winter Dawn’) mg·kg–1. Fruit Ca concentrations ranged between 1,572 (‘Winter Dawn’) and 2,550 (‘Sweet Charlie’) mg·kg–1. ‘Treasure’ had the firmest fruits (1.23 N) and ‘Sweet Charlie’ the least firm (0.72 N). There was a wide range in r-values among the correlations, but ‘Camarosa’ had the highest average correlation between fruit Ca concentration and firmness (r = +0.67) and ‘Treasure’ for leaf Ca concentration and fruit firmness (r = +0.29). Based upon this study, no relationship was found between fruit firmness and Ca concentration. Therefore, the practice of applying supplemental Ca to strawberry plants during its normal growing season may not be beneficial to increasing fruit firmness. Moreover, Ca concentration within strawberry plants should not be used as a predictor of fruit firmness or to substitute for firm fruited cultivars used in production in the selection of lines during breeding.
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JOHN A. MANTHEY

Differences in Secondary Metabolites in Leaves from Orange (Citrus sinensis L.) Trees Affected with Greening Disease (Huanglongbing) (HLB)

Page 285-288

HPLC analyses of methanol extracts of two sets of orange leaves that were symptomatic of HLB showed differences in concentrations of hydroxycinnamates and flavonoids compared to unaffected, healthy leaves. Other differences were also detected in selected total ion currents (TICs) of HPLC–mass spectral (HPLC–MS) analyses of the leaf extracts. One main difference was the higher levels of limonin glucoside in the HLB-symptomatic leaves compared to the healthy leaves. Another difference was an elevated concentration in HLB symptomatic leaves of a compound, possibly an alka­loid, exhibiting a protonated m/z ion at 188 amu, and a violet-colored Ehrlich Reagent spot on TLC.
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SHARON DEA, JEFFREY K. BRECHT, M. CECILIA DO NASCIMENTO NUNES, JEAN-PIERRE ÉMOND, AND KHE V. CHAU

Impact of Environmental Conditions during Distribution on Tomato Fruit Quality and Decay

Page 289-296

Temperature and relative humidity (RH) measurements from two commercial shipments of tomatoes by sea from Puerto Rico to Florida and subsequently within Florida by truck were used to evaluate the consequences of deviations from ideal environmental conditions on fruit quality. Temperature and RH measured at different locations within containers of tomatoes varied from 11.2 to 30.3 °C and from 55.4% to 98.5%, respectively. Laboratory simulations were conducted during two Florida tomato seasons using the 10% most developmentally advanced fruit from lots of commercially packed mature-green tomatoes, which were considered to be the most likely fruit to show effects of non-ideal conditions. Control, bruised, and inoculated (Erwinia carotovora) tomatoes were stored at the best and the worst temperature and RH combinations recorded during the shipping trials, as well as at 12 °C plus 90% RH. Following the simulated shipping period, all fruit were evaluated subjectively for visual and aroma quality, bruised and inoculated fruit were evaluated for incidence and severity of bruising and decay, and control fruit for color, titratable acidity (TA), pH, soluble solids, and ascorbic acid. The simulated worst shipping conditions significantly increased shriveling, soften­ing, and decay incidence, and negatively affected aroma. Virtually all of the inoculated tomatoes held in the simulated worst conditions developed severe decay; however, visual quality was otherwise not affected by shipping conditions. Other than no effect of simulated shipping conditions on TA and pH, no conclusions could be drawn regarding fruit composition since the results varied between repeated experiments. No significant differences in external color were found between the simulated shipping conditions.
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PREETI SOOD, CHRIS FERENCE, JAN NARCISO, AND ED ETXEBERRIA

Effects of Laser Labeling on the Quality of Tangerines during Storage

Page 297-300

Etching the required information on fruit and vegetables is an alternative means to label produce. A low energy CO2 laser beam etches the surface with alphanumerical characters showing the contrasting underlying layer. These etched surfaces can promote water loss and potentially allow pathogen entry. Studies were conducted to measure water loss, peel appearance, and potential decay in laser labeled tangerine (Citrus reticulata) during storage. Laser labeled fruit stored at 10 °C and two different relative humidities (RH) (95% and 65%) for 5 weeks showed no increase in decay compared to control non-etched fruit, suggesting that laser labeling does not facilitate decay. These observations were confirmed by experiments where a suspension of Penicillium digitatum spores was applied on fruit surfaces before and after etching. No decay was observed in either case. Laser etching of agar plates covered in Penicillium digitatum spores reduced germination at the lasered areas. Water loss from etched areas and label appearance were determined during storage. Water loss leveled off after one day in storage and appearance deteriorated proportional to laser exposure times and ambient relative humidity.
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MICHELLE D. DANYLUK, LORETTA M. FRIEDRICH, AND REZA EHSANI

Microbiological Evaluation of Mechanically Harvested Citrus Fruit

Page 301-303

Significant reductions in harvesting costs will be necessary in coming years for Florida to continue to compete in the international citrus industry. Two steps are involved in the mechanical harvesting (MH) of citrus fruit: removal of fruit from the tree and collection of fruit (by a catch-frame device or retrieval of fruit from the ground). This study evaluates the microbiological aspects of mechanically handled fruit with respect to fruit surface microflora and cor­responding fruit juice microflora. Four replicates of mechanical harvesting were performed, including two catch-frame (CF) replicates and two pick-up machine (PU) replicates. For each replicate, three treatment groups were evaluated: 1) hand-harvested fruit (control); 2) ground fruit (picked up directly from ground following canopy shaking); and 3) mechanically harvested (MH) fruit (collected from the OXBO pick-up machine or from the goat following collection on a catch frame). Microbial analysis included a total plate count (TPC), an acidophilic organism count (OSA), and generic Escherichia coli and Salmonella testing on pooled samples of five oranges. Juice samples, from each fruit, were subjected to the same tests. The amount of sand found on the surface of fruit was measured. Hand-harvest control fruit generally had fewer microbes on the surface of the fruit than either ground or MH fruit on both TPC and OSA. Juice corresponding to the control fruit also generally had fewer microbes on both TPC and OSA than the juice corre­sponding to ground or MH fruit. However, no real trends can be attributed to the harvest method for all runs. Generic E. coli was detected in 10 pooled orange samples (five CF and five PU) and Salmonella spp. was not detected in any of the pooled fruit or juice samples. Sand levels on PU MH samples were significantly higher than those found on CF MH, ground, or control fruit.
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JIUXU ZHANG

Detection of Microbial Populations on Freshly Packed Florida ‘Valencia’ Oranges

Page 304-306

Commercial fresh citrus fruit generally receive appropriate postharvest handling and treatments to ensure their safety and high quality. Surface microbial populations on freshly packed ‘Valencia’ oranges obtained from six commercial packinghouses, representing different citrus growing regions in Florida, were studied using PetrifilmTM microbial count plates. The experimental results showed that yeast and mold, aerobic, and coliform bacteria were detected on the surfaces of tested ‘Valencia’ oranges. Freshly packed ‘Valencia’ oranges from two packinghouses had significantly higher (P < 0.05) levels (148.26 to 233.37 CFU/cm2) of yeast and mold counts than those (0.83 to 7.03 CFU/cm2) of the other four packinghouses. Aerobic bacterial levels on freshly packed ‘Valencia’ oranges ranged from 1.54 to 3.01 log CFU/cm2. A low level of coliform bacteria (0.01 to 1.98 CFU/cm2) was observed from all tested fruit. No E. coli was detected for any fruit tested. The experimental results indicate that Florida commercially packed ‘Valencia’ oranges appear to have no potential E. coli related safety risks to the consumers.
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WEIYANG ZHOU, WILBUR WIDMER, AND KAREL GROHMANN

Developments in Ethanol Production from Citrus Peel Waste

Page 307-310

The Florida citrus juice industry produces about 3.5 to 5.0 million tons of wet peel waste annually. This material currently is dried and sold, often at a loss, as cattle feed to dispose of the waste residue. Profitability could be greatly improved if higher value products could be developed and produced from the peel waste. In this paper, the development of a new process to make ethanol along with improved recovery of D-limonene from citrus peel waste is discussed. The process consists of four parts: pretreatment to remove and recover D-limonene, simultaneous saccharification and fermentation (SSF) to produce ethanol, distillation to remove the ethanol and treatment of the residue for use as cattle feed or other co-products. Pilot plant studies have demonstrated that citrus processing waste can be fermented to produce ethanol (approximately 4% w/v) with D-limonene obtained as co-product. In order to design an efficient and cost-effective distillation column to strip off ethanol, the heat transfer coefficient and specific heat of fermented citrus processing waste was measured under forced convection using a heat exchanger. The technical difficulties of stripping off ethanol from fermented peels are also discussed. This new technology provides an alternative disposal of citrus peel waste in the citrus industry.
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RANDALL G. CAMERON, GARY A. LUZIO, WILBUR W. WIDMER, AND MUHAMMAD IQBAL

Biosorption Properties of Citrus Peel Derived Oligogalacturonides, Enzyme-modified Pectin and Peel Hydrolysis Residues

Page 311-314

A citrus processing industry priority is obtaining added value from fruit peel. Approximately one-half of each processed fruit is added to the waste stream. Peel residue is composed mainly of water (~80%), the remaining 20% (solid fraction) consists of pectin, soluble sugars, cellulose, proteins, phenolics, etc. Viewing these constituents in light of exploiting potential functionality and creating added value at the same time as diverting material away from the feed mill or land fill, pectin provides enormous opportunity. To create a new technology centered on pectin structure and concomitant functionality, we are investigating methods to precisely engineer pectin structure and correlate it to function. A valu­able pectin functionality, resulting from its polyanionic character, is its biosorption capabilities. In the past several years we have developed analytical techniques and biochemical methods to enzymatically modify pectin structure, characterize these structural alterations and determine their effect on rheology and calcium sensitivity. Here we present data on the biosorption properties of modified pectins and pectin fragments using lead as a model cation. The great­est Pb sorption capacity (Mean = 373.3 mg·g–1; S.E. = 1.595; P > 0.001) was observed in the Medium DP size-class of galacturonic acid oligomers. A comparison of enzymatically demethylated (blockwise) homogalacturonans indicated that the 60% and 50% DM pectins treated at pH 4.5 had a significantly greater sorption capacity than higher DM or pH 7.5 treated samples.
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GARY A. LUZIO

Microwave Release of Pectin from Orange Peel Albedo Using a Closed Vessel Reactor System

Page 315-319

Pectin was extracted from Moro blood orange in a closed vessel reactor heated with microwave irradiation. Time of heating was either 2 minutes at 110 °C or 210 minutes at 75 °C at pH values of 1.7 to 2.8. A run at 75 °C and at pH 1.7 with resistive heating was additionally performed to simulate industrial process conditions. The highest recovery of pectin [anhydrogalacturonic acid (AGA) of 3.44 milligram per milliliter] was observed at 110 °C and pH 1.7 with microwave heating but the degree of methylation (DM) under these conditions was the lowest at 50.3 percent. A DM of 72.7 percent was observed at 110 °C and pH 2.8, but the pectin concentration was lower at an AGA value of 2.08 mg per milliliter. At pH 2.2 both the DM and AGA values were intermediate between the other two reaction conditions sug­gesting that lower pH improves yield but at the expense of a lower DM value. Molecular weight changes were observed with the various heating and pH values, but the largest effects were on AGA recovery and DM. The data suggests that by careful selection of pH and temperature, acceptable yields of pectin using microwave heating can be obtained while preserving a significant portion of the DM.
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KYUNG MYUNG, JAN A. NARCISO, AND JOHN A. MANTHEY

Removal of Grapefruit Juice Furanocoumarins by Four Edible Fungi

Page 320-321

Furanocoumarins (FCs), a class of phenolic compounds, are known to inhibit the human cytochrome P450 3A4 (CYP 3A4) activity responsible for the metabolism of certain medications. This inhibition increases the oral bioavailability of these medications, leading to potential toxic effects. These interactions, overriding the potential health benefits of grapefruit consumption, have adversely affected the grapefruit industry, and have led to a need to remove the FCs from grapefruit juice (GFJ). Previously, we showed that autoclaved Aspergillus niger adsorbs FCs in GFJ, and that the fungus-treated GFJ showed a reduced inhibition of CYP 3A4. However, A. niger is not an edible fungus, thus prompt­ing us to investigate edible fungi. In this study, autoclaved edible ascomycetes (Morchella esculenta and Monascus purpureus) and basidomycetes (Pleurotus sapidus, and Agaricus bisporus) were mixed with GFJ, and the levels of two of the major furanocoumarins 6´,7´-dihydroxybergamottin (DHB) and bergamottin (BM) were compared in the treated GFJ and in the control, untreated GFJ. These FCs were removed by the heat-killed fungi, suggesting that production of FC-removed GFJ may be achieved.
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MARK A. RITENOUR, BRIAN J. BOMAN, CUIFENG HU, JACQUELINE K. BURNS, AND JEAN BERTRAND CONTINA

Effect of Pre- and Postharvest Factors on Fresh Grapefruit Peel Breakdown

Page 322-325

During the 2006–07 and 2007–08 fresh citrus seasons, reports of peel breakdown problems were more frequent and severe than usual. Plots were established during the 2007–08 season in commercial groves using standard fresh fruit growing practices to evaluate pre- and postharvest factors influencing peel breakdown. Preharvest treatments included up to three foliar potassium (K) sprays (March, October, and January) or withholding irrigation for up to 2 months before harvest. In one commercial block, foliar mono-potassium phosphate (MKP) was applied at 23.5 lb MKP per acre (0–52–34; 8 lb K2O per acre) with 4 lb per acre low-biuret urea (46–0–0) applied at a total volume of 125 gal per acre. In another block, the grower applied 3 gal per acre of a commercial 3–18–18 formulation at a total volume of 250 gal per acre. Postharvest treatments included holding fruit for 3 days at 30%, 55%, or 100% (including wetting the fruit) RH before washing and storing at 70 °F under ambient RH. In the first block, preharvest foliar MKP treat­ments applied 2 months or more before harvest did not significantly reduce peel breakdown. However, stem-end rind breakdown was significantly reduced in the second block with foliar 3–18–18 applied 2, 3, or 4 weeks before harvest. Blocking irrigation and rainfall for 49 days before harvest increased peel breakdown, whereas wetting the fruit after harvest and maintaining high postharvest RH reduced peel breakdown.
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KIMBERLY MOORE

Evaluation of Cow and Swine Manures to Grow Impatiens (Impatiens wallerana Hook. f.) in Container Production

Page 326-330

Two experiments were conducted to compare the growth of impatiens plants (Impatiens wallerana Hook. f.) in sub­strates amended with swine manure or dairy manure. In Experiment 1, impatiens plants were grown in substrates amended with 0.88, 1.77, 3.54, or 5.30 g of N per pot incorporated as Nutricote 13N–5.7P–10.8K plus minors type 100, swine manure, or dairy manure. Impatiens plants grown with Nutricote had greater shoot dry weights and final plant quality ratings than plants grown with equivalent N rates of swine or dairy manure. Impatiens plants grown with 3.54 g and 5.30 g of N from swine manure were considered saleable while none of the plants grown in dairy manure were considered saleable. In Experiment 2, impatiens plants were transplanted into Pro-mix BX, or Pro-mix amended with 10% swine manure or 10% dairy manure. All plants were top-dressed with 0.33, 0.65, or 1.30 g of N from Nutricote 13N–5.7P–10.8K plus minors type 100. Highest impatiens quality and greatest shoot dry weights were observed for plants grown in Pro-mix with 0.65 and 1.30 g of N from Nutricote. The combination of 10% swine manure with 0.33 and 0.65 g of N and 10% dairy manure with 0.33 g of N also produced saleable quality plants. It appears from this work that a combination of 10% or less swine or dairy manure with commercial controlled-release products will produce saleable quality impatiens plants.
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JIMMY SOCASH AND HENRIQUE MAYER

Trees, Urban Environments, and Soil Volumes

Page 331-333

Endless expansion of urban areas throughout Florida has caused rampant destruction of forested lands, resulting in exaggerated increases in temperature and the creation of new urban spaces devoid of natural liveable conditions. For­tunately, this problem has not gone unrecognized and many governmental and municipal agencies have been proactive in requiring extensive new plantings as part of “development.” However, due to the precious value of urban real estate, open spaces and tree planting opportunities are minimal and more often than not, the urban tree plantings are left to the marginal corners and most undevelopable places on a typical site. This presentation will attempt to demonstrate that development regulations requiring tree plantings for urban areas are vital. However, without adequate soil volume for urban tree plantings, these tree requirements are doomed to fail. In order to enhance tree growth in urban areas, new technologies such as CU-Structural Soils, Deep Root Silva Cells and use of permeable pavements are available. Incorporation and use of these and other similar measures may help provide better growing environments for urban trees.
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STACIA L. DAVIS, MICHAEL D. DUKES, AND GRADY L. MILLER

Irrigation Application Using Evapotranspiration-based Irrigation Controllers

Page 334-337

Despite limited water resources, typical homes in Florida have in-ground irrigation systems utilizing automated timers that have been shown to increase outdoor water use. The need for landscape irrigation is likely to continually grow with increased population growth and home construction in Florida. Evapotranspiration-based controllers, or ET controllers, are irrigation controllers that use an estimation of evapotranspiration (ET) to schedule irrigation. Three ET controller systems were selected to evaluate their ability to apply irrigation compared to two time-based schedules developed from UF-IFAS recommendations. Five treatments were replicated four times totaling 20 plots, each measur­ing 7.62 m × 12.2 m. The plots, constructed at the UF Gulf Coast Research and Education Center, were partitioned into 65% St. Augustinegrass (Stenotaphrum secundatum) and 35% mixed-ornamentals to represent a typical Florida landscape. The irrigation treatments were as follows: Smart Line Series controller (Weathermatic, Inc., Dallas, TX), Intelli-sense (Toro Company, Inc., Riverside, CA), Smart Controller 100 (ETwater Systems LCC, Corte Madera, CA), a time-based treatment derived from UF-IFAS recommendations, and a time-based treatment that was 60% of UF-IFAS recommendations. Results were quantified by comparing weekly water application depths and turfgrass quality.
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JAMES J. MUCHOVEJ, OGHENOKOME U. ONOKPISE, MARY J. WILLIAMS, AND KENNETH LIVINGSTON

Growing Medium Effects on the Establishment of Muhlenbergia capillaries

Page 338-339

1Department of Horticulture, 306 Perry Paige Bldg., Florida A&M University, Tallahassee, FL 32307

The establishment and survival of Muhlenbergia capillaris was determined by planting native material in four different potting media. A clump of tillers was harvested, trimmed at a height of 15 cm, and the roots trimmed at a length of 3 cm. The treatments, in four replicates, consisted of planting densities of 1, 2, 4, 8, or 16 tillers planted in each of four different potting media. The potting media were i) a mixture of 80:10:10 bark : sand : peat (v:v); ii) 80:20 peat : perlite (v:v); iii) 60% composted pine bark; and peat, perlite, vermiculite, horticultural grade charcoal, and lime (v:v); and iv) 1:1:1 peat : sand : perlite (v:v). Data collected monthly for 6 months included number of tillers surviving, and plant height. In general, higher planting densities gave greater survivability. Also, the mixtures ii and iii provided greater rates of survival. Plant height was favored by planting in mixture iii.
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MARY SHEDD, MICHAEL D. DUKES, AND GRADY L. MILLER

Effect of Irrigation Control on St. Augustinegrass Quality and Root Growth

Page 340-345

Due to water shortages, landscape irrigation is limited in many areas of Florida to 1 or 2 days per week. Three frequen­cies of irrigation on ‘Floratam’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze.] were evaluated based on root growth and turf quality. Six irrigation treatments were established using rain sensors set at rainfall thresholds of 3 and 6 mm and irrigation schedules of 1, 2, or 7 days per week. The volume applied per week was the same for all treatments. In addition there was a reduced irrigation treatment set for 2 days per week, with a 40% reduction in scheduled depth of application compared to the other treatments, a 2-day per week treatment without a rain sensor and a non-irrigated treatment. Root mass samples were taken once in 2006 and once in 2007 (15 cm and 30 cm). Analysis showed that frequency of irrigation did not have a significant impact on depth of root growth. The majority of the root mass was in the top 15 cm with 87% in 2006 and 75% in 2007. Turf quality was impacted by irrigation frequency, with 2 and 7 days of irrigation per week typically producing better quality than 1 day.
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ROBERT H. STAMPS, JIANJUN CHEN, SEENIVASAN NATARAJAN, AND JUANITA POPENOE

Evaluations of New Controlled-release Fertilizers for Use in Production of Interiorscape and Landscape Plants

Page 346-349

Controlled-release fertilizers (CRFs) are commonly used in the production of ornamental plants. They are often used to reduce labor costs, provide consistent nutrient availability over time, and potentially reduce nutrient losses due to leaching. Studies were initiated in Apopka, FL, in May 2007 to compare two 16–8–12 experimental CRFs, one with a 6-month (ECRF6) and one with a 9-month release term (ECRF9), to a commonly used commercial CRF with a similar release term (Osmocote® Plus 15–9–12 or Nutricote® Total 17–7–8 type 270/70, respectively). Tissue-cultured liners of interiorscape cultivars Dieffenbachia ‘Camille’ and Spathiphyllum ‘Ty’s Pride’ were potted into a sphagnum peat-based container medium and grown in a shaded greenhouse using one of the two 6-month release materials. Cutting-derived liners of landscape shrubs Loropetalum chinense ‘Burgundy’ and Viburnum odoratissimum were transplanted into containers filled with a pine bark-based mix and grown in full sun using one of the two 9-month release products. The interiorscape plants grew equally well using ECRF6 as with the Osmocote® Plus. Loropetalum growth and grades were similar using both 9-month release fertilizers; however, growth of viburnums fertilized with ECRF9 was somewhat greater after four months than those fertilized with Nutricote®. Initially, nitrate-nitrogen (NO3-N) leaching, determined using the pour-through method, was greater for ECRF9 than for Nutricote®. Subsequent leachate concentrations from containers with plants were mostly similar for the two products and ranged from 4 to 21 ppm [mg·L–1].
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LAURIE TRENHOLM AND DONALD P. RAINEY

Update on Turf Fertilizer Rules and Regulations and How to Conduct a Green Industry Best Management Practices Training

Page 350-352
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ROBERT T. MCMILLAN, JR., AARON J. PALMATEER, AND WAGNER A. VENDRAME

Cercospora Leaf Spot Caused by Cercospora dendrobii on Dendrobium antennatoum Lindl. and Its Control

Page 353-355

Cercospora leaf spot disease of Dendrobium spp. has been reported in Florida, Thailand, and most of the tropical areas of the world where dendrobiums are grown. It most commonly occurs in southern Florida and has been significant in dendrobium production. Other species of cercospora leaf spot pathogens are occasionally found on other genera of orchids, including Angraceum, Cattleya, Odontoglossum, Brasavola, Broughtonia, Epidendrum, and Schomburgkia. Leaf lesions on the Dendrobium are at first noted on the undersurface of the leaf as pale yellow sunken spots, 1 to 3 mm in diameter. With time, the spots continue to enlarge in a circular or irregular pattern and eventually may cover the whole underside of the leaf. Later the spots become slightly sunken and purple-black with the developing margin remaining yellow. Following the appearance of the spots on the lower leaf surface, a corresponding yellow–pale green area can be seen on the upper leaf surface. Eventually the spots turn purplish-black or black. Heavily infected leaves abscise. Prolonged periods of leaf wetness should be avoided. Chlorothalonil and thiophanate-methyl are labeled for control of cercospora leaf spot on orchid in the United States. Results from cercospora fungicide trials conducted in 2005 showed that the BASF 516 04 F (pycadostrobin + boscalid) 38%WG at 340.2 g per 379 L of water and pyraclostrobin 20%WG at 226.8 g per 379 L of water were significantly effective.
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HENRIQUE MAYER, EDWARD SKVARCH, PAM MATTIS, AND REBECCA JORDI

Designing an Integrated Pest Management (IPM) Program for Hispanic Landscapers

Page 356-357

According to a 2005 University of Florida Nursery and Landscape Industry Economic analysis report made by John J. Haydu and Alan W. Hodges, Florida’s landscape sector installation, maintenance, and design accounts for $5.255 billion sales per year. Almost 30% ($1.582 billion) is attributed to landscape maintenance business. The use of IPM principles in Florida’s 6 million acres of land, in order to minimize pest problems and apply chemicals only when ap­propriate, is a key concept if we want to live in a sustainable environment. Traditionally, the majority of Extension landscape management programming and educational publications available on Integrated Pest Management (IPM) topics have been produced and directed towards an English-speaking audience. However, in Florida demographics have rapidly changed in the last 10 to 15 years and the number of Spanish-speaking landscape management companies has increased. Twenty-eight participants from 14 different companies completed the IPM training. In a telephone survey conducted 6 months after the class, participants indicated they were using the class handouts anywhere from daily to once per month with average use of once to twice a week. The survey also indicated that as a result of the training, the participants felt more confident talking to their clientele on pest-related topics.
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MARY LAMBERTS, HENRIQUE MAYER, RUBEN REGALADO, ADRIAN HUNSBERGER, AND CATHARINE MANNION

Developing a Bilingual Video/Video Podcast to Teach Clients How to Apply a Soil Drench Insecticide to Control a New Pest, the Fig Whitefly

Page 358-359

In Aug. 2007, the Miami–Dade County Extension office received numerous phone calls about a new problem with Ficus hedges. The cause was identified as the fig whitefly [Singhiella simplex (Singh)] in Oct. 2007. By Nov. 2007, a management protocol was developed, which included the use of a soil drench with a systemic neonicotinoid insecticide to help preserve natural enemies. Because there were many questions about application techniques from industry pro­fessionals, reports of misapplications and concerns about environmental impacts, the Miami–Dade County Extension horticultural staff decided that the best way to educate all possible clients was with a bilingual video demonstration of proper application techniques. The video was produced in-house using Extension educators and an Extension Advisory Committee member who is also an industry professional as the “talent.” It includes information for both homeowners and professionals on proper methods of applying a soil drench. This was converted into segments and adapted for downloading via either a dial-up or a DSL connection and is posted on the Miami–Dade County Extension website. It has also been used in several workshops.
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DOUGLAS L. CALDWELL

Staining Associated with Oxhorn Bucida (“Black Olive”) Trees (Bucida buceras): The Caterpillar and Eriophyid Mite Connection

Page 360-362

Oxhorn bucida (Bucida buceras L.), also known as black olive, is used as a shade tree in southern Florida landscapes and street plantings. One negative aspect associated with this tree is a rusty staining of driveways and other objects beneath the canopy. This report documents that the objectionable staining is not caused so much by the normal fruit or foliage, but rather is the result of a series of arthropod infestations. Observations reveal the dark staining is associ­ated with frass from a noctuid caterpillar, Characoma nilotica, which feeds on the foliage and flowers and also bores into the string bean-like galls caused by an eriophyid mite, Eriophyes buceras Cromroy.
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FORREST W. HOWARD, ROBERT W. PEMBERTON, AND HONG LIU

Erythrina Gall Wasp, Quadrastichus erythrinae (Hymenoptera: Eulophidae) in Florida, and Susceptibility of Erythrina herbacea (Fabaceae)

Page 363-369

Erythrina gall wasp (EGW), Quadrastichus erythrinae Kim, and the extent of its galling and associated damage to Ery­thrina spp. hosts were observed in a research nursery and in natural and landscaped areas in southern Florida. In the research nursery, galling and resultant damage to Erythrina herbacea L., a native plant, were highly variable on four dates during a 1-year period. On one examination date, when the susceptibility levels of three species of Erythrina were compared, there was a higher mean percentage of galled leaves on Erythrina variegata L. than on Erythrina herbacea, and minimal galling on Erythrina humeana Sprengel. Based on several criteria, E. variegata was the most susceptible of these hosts. Preliminary field observations on the behavior of EGW are reported. Erythrina amazonica Krukoff is reported as a new host of EGW.
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NAMGAY OM, ROBERT MCSORLEY, AND JOHN J. FREDERICK

Response of Cut Flowers and Bedding Plants to Root-knot Nematodes

Page 370-373

Five separate experiments were conducted to test the susceptibility of different cut flowers and bedding plants to root-knot nematodes, Meloidogyne incognita (Kofoid & White) Chitwood race 2, M. javanica (Treub) Chitwood, and M. arenaria (Neal) Chitwood. The first set of experiments involving two separate tests was conducted in Oct. 2007. The first two tests consisted of seven cultivars of cut flowers and bedding plants grown under greenhouse conditions to test their susceptibility to root-knot nematodes, Meloidogyne incognita race 2 and M. javanica. Cultivars examined included ‘Thumbelina’ and ‘Envy’ zinnia (Zinnia elegans L.); ‘Petite’ and ‘Jaguar’ marigold (Tagetes patula L.), and ‘Snowdrift’ marigold (T. erecta L.); ‘Dwarf Jewel Blend’ nasturtium (Tropaeolum minus L.); and ‘Potomac Pink’ snapdragon (Antirrhinum majus L.). In a separate experiment, ‘Potomac Pink’ snapdragon plants were tested to de­termine their response to M. arenaria and varying concentrations of M. incognita race 2 inoculum. The last two tests were conducted in Dec. 2007 and involved M. incognita race 2 and M. javanica. The cultivars tested included ‘Butterfly Blend’ delphinium (Delphinium grandiflorum L.); ‘Silver Princess’ Shasta daisy (Chrysanthemum maximum Raymond); ‘Blue Bedder’ salvia (Salvia splendens Ker-Gawl); ‘Chabaud Giant’ carnation (Dianthus caryophyllus L.); ‘Dwarf Magic Carpet’ and ‘Potomac Pink’ snapdragons. Based on the numbers of nematodes recovered from the root systems and the soil, nasturtium and the two cultivars of snapdragon were susceptible to the root-knot nematodes evaluated while marigold, zinnia, salvia, and carnation were poor hosts (P ≤ 0.05). Shasta daisy was moderately susceptible. ‘Potomac Pink’ snapdragon was also equally susceptible to both M. incognita and M. arenaria.
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KENNETH T. GIOELI

Tame Invasives Portal: A Solution for Your Life

Page 374-376

Local, state, and federal governments in Florida spend an estimated $12,500,000 annually to manage four invasive plants: old world climbing fern (Lygodium microphyllum), tropical soda apple (Solanum viarum Dunal), Brazilian pepper-tree (Schinus terebinthifolius), and melaleuca (Melaleuca quinquenervia). Often times, these invasive plants can not be adequately managed utilizing traditional mechanical, chemical, and cultural practices. Biological control is another proven, yet under utilized, strategy that can be used to manage invasive plants. Unfortunately, there is a lack of understanding of the role of biological control as an effective tool in our efforts to control invasive plants. A web portal entitled “TAME Invasives: A Solution for Your Life” is made available by the University of Florida at http://pesticide.ifas.ufl.edu. This portal features research-based information, multimedia products and online coursework that focus on the management of these four invasive pest plants. Online courses have been developed to teach course participants how to 1) manage these invasive plants; 2) use herbicides in the most effective manner that is safe for people and the environment; and 3) understand the role of biological control as an essential Integrated Pest Management (IPM) tool for the management of these invasive plant species.
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RUSSELL F. MIZELL, III, T. CHARLES RIDDLE, AND ANN S. BLOUNT

Trap Cropping System to Suppress Stink Bugs in the Southern Coastal Plain

Page 377-382

A trap cropping system was developed to manage the stink and leaffooted bug pests in the southern coastal plain and perhaps other areas. The biologically based strategy can be customized for any planting season from spring to fall. Plantings are established in small plots adjacent to the cash crop using standard cultural practices. A mixture of species and continuous management is required to ensure optimum food availability in the trap crop to out compete the cash crop for stink bug feeding. Triticale, sorghum, millet, buckwheat, and sunflower are the main species recommended. Small-acreage growers may wish to plant trap crops in large containers for portability. Millet, sorghum, and buckwheat may be ratooned (new growth after mowing) to extend the life of the trap crops relative to the cash crop. Augmenta­tion of insect pollinators, generalist predators and parasites including those of stink bugs is an emergent property of these plantings. Stink bugs can be killed in the relatively smaller areas of the trap crop by hand, with sweep nets, or with insecticide applications.
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JAMES J. MUCHOVEJ, OGHENEKOME U. ONOKPISE, AND SUSAN BAMBO

Comparison of Ramet and “Wild Type” Establishment for Cogongrass, Imperata cylindrical

Page 383-384

The establishment of Imperata cylindrica was compared by planting greenhouse grown ramets and field collected tillers (wild type). The ramets were collected taking rhizomes from a single plant, cutting them in pieces that contained two nodes, and then planting these in a composted pine bark potting mix. The wild type was produced by harvesting field-grown cogongrass, trimming the roots to 2 cm, and planting individual tillers in the same potting mix. All plants were then placed under mist until they had become established. The ramets and wild types were then potted in a mixture of 80:10:10 bark:sand:peat (v:v); in 30-cm-diameter pots. The pots were then placed on greenhouse benches. Data collected every 2 weeks for tillers per plant indicated that the wild type group had a significantly better production. At the later stages of development (6, 12, 18, or 24 weeks), wild type produced plants had greater length of tillers; and dry weights of tops, rhizomes and roots.
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LELAN PARKER AND JUANITA POPENOE

Using Banker Plants as a Biocontrol System for Spidermites

Page 385-386

Biological control is the most environmentally friendly control measure for pests, but the most difficult to learn. Greenhouse and nursery growers have been slow to adopt biocontrol partly because of the difficulty in identifying, purchasing, and monitoring biocontrol agents. A banker plant system to control one of the most common greenhouse pests—spidermites—was used in a grower demonstration project. The obstacles to effective use were identified as how often to reintroduce infested banker plants and the best way to distribute the banker plants in the crop. The results of the demonstration project were used in a grower field day to get more growers to try, and hopefully adopt some biocontrol agents.
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GARY K. ENGLAND

Natural Solutions for Your Gardening Life

Page 387-388

There are a number of tactics available to enable homeowners to manage pests in the landscape with minimal use of synthetic pesticides. Utilization of this concept can result in a healthy landscape while reducing the potential to harm oneself and the environment that is associated with some synthetic pesticides available to homeowners. Taking all the measures possible to grow healthy landscape plants is the first step. Putting the right plant in the right place and fol­lowing good horticultural practices help to achieve the goal of healthy and pest free plants. Taking steps to identify and eliminate pests will help keep populations low. To do this it is necessary to learn the key pests to expect with the plants you are growing. If pest populations begin to expand in the landscape, there is an array of tactics that may be employed. Pests can be managed by mechanical means such as picking, washing and trapping. Enhancing and augment­ing natural pest managing organisms, such as insect predators and parasites, help to maintain pest populations within an acceptable range. There are some non-synthetic products available to homeowners that may assist in managing damaging pests of the landscape.
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CATALINA MOYER AND NATALIA A. PERES

Evaluation of Biofungicides for Control of Powdery Mildew of Gerbera Daisy

Page 389-394

Powdery mildew caused by the fungus Erysiphe cichoracearum DC. or Podosphaera fusca (Fr.) S. Blumer is a com­mon disease on gerbera daisies (Gerbera jamesonii Bolus ex. Hook f.) grown in Florida. This disease affects all parts of the plant and reduced plant quality is the main component of economic loss. The effect of calcium silicate, potassium silicate, and the biofungicide products Actigard (acibenzolar-S-methyl), K-phite (phosphorous acid), Milstop (potas­sium bicarbonate), Tricon (boron, orange oil and organic surfactants), Cease (Bacillus subtilis) and AgSil (potassium silicate) were evaluated in highly susceptible (‘Snow White’ and ‘Orange’) and moderately susceptible (‘Hot Pink’ and ‘Fuchsia’) gerbera cultivars. Results suggested that neither calcium silicate nor potassium silicate were effective in suppressing powdery mildew in gerbera daisy. The biofungicides products Actigard, Agsil, Cease, K-phite, Milstop and Tricon, suppressed powdery mildew of gerbera daisy compared with untreated plants; however, these products were not as effective as the fungicide program of Heritage alternated with Eagle. Among the biofungicide products tested K-phite, Millstop and Tricon were the most effective in reducing disease severity. Thus, biofungicide products may be used as an alternative to reduce the use of fungicides for suppressing powdery mildew of gerbera daisy.
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ZHANAO DENG and BRENT K. HARBAUGH

Caladium Breeding: Progress in Developing Lance-leaved Cultivars

Page 395-398

Caladiums are commonly grown as container or landscape plants in Florida. Historically, fancy-leaved cultivars have dominated the market. During the past two or three decades, the demand for lance-leaved cultivars has increased due to their inherent characteristics including short plants, resilience to environmental stresses, and ease of forcing in containers. However, the number of lance-leaved cultivars has been limited with few choices available for leaf color or color pattern, and many of the available lance-leaved cultivars have poor tuber yields. Consequently, tuber production for these cultivars is difficult and less profitable compared to production of fancy-leaved cultivars; this has led to a short supply and higher price for tubers of lance-leaved cultivars. Since its beginning in 1976, developing new lance-leaved cultivars with improved or novel foliar characteristics and good tuber yield has been a major breeding objective of the University of Florida’s Institute of Food and Agricultural Science’s caladium breeding program. ‘Florida Sweetheart’ was the first cultivar released from this breeding program, followed by ‘Florida Red Ruffles’, ‘Florida Irish Lace’, ‘Florida White Ruffles’, and ‘Florida Whitewater’. Some of them have become very popular in the Florida caladium industry. In more recent years, efforts have been made to improve disease resistance, sun tolerance, and cold tolerance in lance-leaved cultivars. Dozens of elite lines have been developed and evaluated for their tuber production, landscape performance in the sun as well as in the shade, and container performance. A number of these lines have performed outstandingly; three of them were released as new cultivars in early 2008.
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EDWARD A. SKVARCH

Comparing the Costs and Educational Value of Delivering Distance Education Programming versus Traditional Face-to-face Classroom Education

Page 399-401

Extension clients have indicated that to remain competitive in a changing industry they need educational program­ming (DeCamp et al., 2001). In the past, this was accomplished through a face-to-face classroom setting (Chambers et al., 2006). Although research has shown that the value of classroom delivery is still important, producers have become concerned with increases in the cost of traveling to a live classroom (DeCamp et al., 2001). In an effort to help curtail costs associated with face-to-face workshops while still delivering pertinent educational resources, a statewide team of University of Florida/IFAS Commercial Horticulture Extension educators began authoring a series of monthly articles in a regional commercial nursery industry magazine. The purpose of this study was to compare costs associated with traveling to a traditional face-to-face classroom situation against costs incurred through receiving the same material via distance education. This study determined the effectiveness, satisfaction, and quality of the resources delivered via distance education.
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LAURIE E. TRENHOLM

Effect of Shade on Performance of St. Augustine Cultivars

Page 402-405

Five St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] cultivars were evaluated for shade tolerance in a greenhouse study at the University of Florida. Cultivars ‘Amerishade’, ‘Delmar’, ‘DeltaShade’, ‘Floratam’, and ‘Palmetto’ were placed in full sun or under shade structures that provided 30%, 50%, or 70% shade in a glasshouse at the Turfgrass Research Envirotron in Gainesville. Evaluations were taken for visual quality, color, and density, leaf clipping weights, leaf length and width, and multispectral reflectance. For the majority of measurements, the cultivars Amerishade and Delmar were the best performers. They maintained acceptable quality levels up to 62% and 55% shade, respectively. Worst performance in shade or sun was seen in ‘Floratam’. Clipping weight declined in all cultivars as shade increased, in spite of increasing leaf length in shade. Reflectance scores showed that there were significant differences in light attenuation between cultivars.
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STEPHEN H. BROWN

Identification of the Four Forms of Plumeria rubra

Page 406-407

The number of Plumeria species range from five to 45. Plumeria rubra L. is apparently the source of many Plumeria cultivars. The species is the parent stock for many color variations and many of the named cultivars we have today. In the past, flower colors of Plumeria rubra were considered distinct species but are now regarded as different forms of the same species. All forms have twisted overlapping corollas, much like the blades of a propeller. Forma acutifolia has white flowers and yellow centers. Forma lutea has yellow flowers. Forma rubra has pink flowers with a tangerine-yellow center and forma tricolor has pale yellow-white flowers with yellow centers and a red or pink rim. Forma rubra has the longest flowering days and is the tallest of the four forms. Flowers of forma acutifolia and forma lutea appear earlier in the year than forma rubra but their flowering days are generally shorter.
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