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Wimauma, FL, United States

Tamang B.,University of Florida | Andreu M.G.,Gulf Coast Research and Education Center | Rockwood D.L.,University of Florida
Agroforestry Systems | Year: 2010

Florida citrus and vegetable crops generate billions of dollars in revenue every year. However, wind, freezing temperatures, hurricanes, and diseases negatively impact production. Windbreaks located perpendicular to the prevailing wind can increase farm production simply by reducing wind and modifying microclimate. Windbreaks can also help in managing pathogens such as citrus canker (Xanthomonas campestris pv. citri). To study the modification of wind speed, temperature, and relative humidity on the leeside of single-row tree windbreaks in southern Florida, automated weather stations were installed in 2007/2008 at 2 m above the ground along transects perpendicular to a eastern redcedar (Juniperus virginiana) and three cadaghi (Corymbia torelliana) (WB1-WB3) windbreaks. All windbreaks reduced wind speed, with minimum wind speed (~5% of the open wind speed) at two times the distance of windbreak height (2H, where H = windbreak height in m) on the leeside of a E. redcedar (~17% porosity) and at 4H (~3-30% of the open wind speed) and 6H (<50% of the open wind speed) on the leeside of cadaghi windbreaks WB1 (~22% porosity) and WB2 (~36% porosity), respectively, when the wind direction was nearly perpendicular to the windbreaks. Wind speed reduction was observed up to 31 times the windbreak height (31H). Cadaghi windbreaks reduced wind speed on the leeside even during a tropical storm event. Temperatures on the leeside of the windbreaks were warmer during the day and cooler near the windbreaks at night compared to temperature in the open fields. This study demonstrates that single-row tree windbreaks can reduce wind and modify the microclimate to enhance crop production for Florida growers. © 2010 Springer Science+Business Media B.V.

Simonne E.,University of Florida | Hutchinson C.,University of Florida | DeValerio J.,Bradford County | Hochmuth R.,North Florida Research and Education Center | And 8 more authors.
HortTechnology | Year: 2010

The success of the best management practices (BMPs) program for vegetables in Florida is measured by the level of BMP implementation and the improvement of water quality. Both require keeping water and fertilizer in the root zone of vegetables. The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension Vegetable Group has identified the fundamental principles of 1) basing UF/IFAS production recommendations on the rigors of science and the reality of field production; 2) replacing the out-of-date paradigm "pollute less by reducing nutrient application rates" with "improve water management and adjust fertilizer programs accordingly"; 3) engaging growers, consultants, educators, and regulators in open-channel discussions; and 4) regularly updating current fertilization and irrigation recommendations for vegetables grown in Florida to reflect current varieties used by the industry. The group identified 1) developing ultralow-flow drip irrigation; 2) assisting conversion from seepage to drip irrigation; 3) using recycled water; 4) developing controlled-release fertilizers for vegetables; 5) developing real-time management tools for continuous monitoring of soil water and chemical parameters; 6) developing yield mapping tools for vegetable crops; 7) developing and testing drainage lysimeter designs suitable for in-field load assessment; and 8) using grafting and breeding to develop commercially acceptable varieties with improved nutrient use efficiency by improving morphological, biochemical, and chemical traits as new strategies to keep nutrients in the root zone. These strategies should become funding priorities for state agencies to help the vegetable industry successfully transition into the BMP era.

Kumar V.,Tropical Research and Education Center | Seal D.R.,Tropical Research and Education Center | Schuster D.J.,Gulf Coast Research and Education Center | McKenzie C.,Us Horticultural Research Laboratory | And 3 more authors.
Florida Entomologist | Year: 2011

The chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is an emerging pest of many economically important vegetable and ornamental crops grown in the United States. Accurate identification of this pest is a fundamental requirement in development of effective quarantine and management strategies. Using scanning electron microscopy, high resolution images of important taxonomic traits of this pest were produced, which will aid research, regulatory and extension personnel to identify this pest. High resolution images were obtained for identifying characters of S. dorsalis including tergites with antecostal ridges; head with 3 pairs of ocellar setae, metanotum presenting longitudinal striations with medially located pair of setae; veins of forewing presenting widely spaced setae; segment VIII with complete posteromarginal comb of microtrichia; and sternites lacking discal setae but covered with rows of microtrichia except in the antero-medial region. Further, a preliminary comparison of morphological traits of S. dorsalis populations from different geographical regions was conducted, which can help in understanding the phenotype of this pest. Specimens of S. dorsalis were obtained from 5 distinct geographical regions: New Delhi, India; Shizouka, Japan; Negev, Israel; St. Vincent and Florida in the United States. Fourteen morphological characters of each population of S. dorsalis were measured and compared among the 5 populations. No significant differences were observed between the body lengths of the various S. dorsalis populations, which ranged from 0.85 mm (Negev) to 0.98 mm (Florida). When comparing 12 morphological characters, we found no significant differences among New Delhi, St. Vincent, Negev and Florida populations. However, when S. dorsalis populations of these 4 regions were compared with Shizouka, significant differences were detected for either 2 or 5 morphological characters depending on the population, suggesting the Japan population is more robust i.e., longer and wider mesothorax and metathorax, and wider abdomens. Also, the mean lengths of body size among different populations did not vary directly or inversely with latitude.

Wilson S.B.,University of Florida | Wilson S.B.,Indian River Research and Education Center | Knox G.W.,University of Florida | Knox G.W.,North Florida Research and Education Center | And 6 more authors.
HortScience | Year: 2014

A wild-type selection of heavenly bamboo (Nandina domestica) and eight cultivars were evaluated in northern and southern Florida for 144 weeks. Onset of flowering generally began by April andMay in southern Florida and 4 to 8 weeks later in northern Florida. Fruit was first noted 4 to 8 weeks after most cultivars began flowering. Landscape performance and fruit production varied widely among taxa and location. 'AKA', 'Firehouse', 'Firepower', and 'Firestorm' heavenly bamboo did not flower or fruit in either location. Greater plant growth, survival, and fruiting were observed in northern Florida than in southern Florida. In both locations, the wild-type form of heavenly bamboo produced more fruit than 'Alba', 'Gulf Stream', 'Monfar', and 'Moyer's Red'. Seed viability was fairly consistent among fruiting cultivars, ranging from 69% to 89%. Nuclear DNA content and ploidy analysis indicated that all nine nandina cultivarswere diploids, suggesting that tetraploidy is not the genetic cause of the non-fruiting trait in 'AKA', 'Firehouse', 'Firepower', and 'Firestorm'. Results of this study offer insight into future non-invasive heavenly bamboo breeding efforts and emphasize the importance of cultivar and geographic distinctions when regarding the invasive status of a species.

Kebede M.,Haramaya University | Timilsina S.,University of Florida | Ayalew A.,Haramaya University | Admassu B.,International Institute Of Tropical Agriculture | And 8 more authors.
European Journal of Plant Pathology | Year: 2014

Bacterial spot of tomato (BST) is a major constraint to tomato production in Ethiopia and many other countries leading to significant crop losses. In the present study, using pathogenicity tests, sensitivity to copper and streptomycin, and multilocus sequence analysis (MLSA), we identified a diverse group of Xanthomonas strains isolated from central Ethiopia. None of the strains were sensitive to copper or streptomycin. Multilocus sequence analysis was used to compare Ethiopian strains with representative Xanthomonas strains from a worldwide collection based on DNA sequences of six housekeeping genes (lacF, lepA, gyrB, fusA, gltA and gapA) and hrpB genes. Phylogenetic analysis of the concatenated sequences showed that X. gardneri, X. vesicatoria and X. perforans were associated with BST in Ethiopia, whereas Xanthomonas euvesicatoria was absent from the Ethiopian sample. There was no genetic diversity among the isolated strains belonging to X. gardneri and X. perforans. However, two X. vesicatoria haplotypes were identified indicating at least two different sources of introduction of X. vesicatoria to Ethiopia. All of the X. perforans strains were only pathogenic on tomato and were T3 strains with the exception of one identified as tomato race 4 (T4). The X. gardneri and X. vesicatoria strains were tomato race 2 (T2), but were variable in pepper race determinations indicating variation in effectors among strains. © 2014, Koninklijke Nederlandse Planteziektenkundige Vereniging.

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