Southwest Florida Research and Education Center

Saint Pete Beach, FL, United States

Southwest Florida Research and Education Center

Saint Pete Beach, FL, United States
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Leiva J.A.,University of Florida | Nkedi-Kizza P.,University of Florida | Morgan K.T.,Southwest Florida Research and Education Center | Kadyampakeni D.M.,Citrus Research and Education Center
PLoS ONE | Year: 2017

Imidacloprid (IMD) is a neonicotinoid pesticide soil-drenched to many crops to control piercing-sucking insects such as the Asian citrus psyllid (ACP). Neonicotinoids are persistent in the environment and transport analyses are helpful estimate leaching potential from soils that could result in groundwater pollution. The objective of this study was to analyze IMD breakthrough under saturated water flow in soil columns packed with three horizons (A, E, Bh) of Immokalee Fine Sand (IFS). Also, we used the dimensionless form of the convective-dispersive model (CD-Model) to compare the optimized transport parameters from each column experiment (retardation factor, R; fraction of instantaneous-to-total retardation, β; and mass transfer coefficient, ω) with the parameters obtained from sorption batch equilibria and sorption kinetics. The tracer (Cl-) breakthrough curves (BTCs) were symmetrical and properly described by the CD-Model. IMD BTCs from A, Bh, and multilayered [A+E+Bh] soil columns showed steep fronts and tailing that were well described by the one-site nonequilibrium (OSNE) model, which was an evidence of non-ideal transport due to IMD mass transfer into the soil organic matter. In general, IMD was weakly-sorbed in the A and Bh horizons (R values of 3.72 ± 0.04 and 3.08 ± 0.07, respectively), and almost no retardation was observed in the E horizon (R = 1.20 ± 0.02) due to its low organic matter content (0.3%). Using the HYDRUS-1D package, optimized parameters (R, β, ω) from the individual columns successfully simulated IMD transport in a multilayered column mimicking an IFS soil profile. These column studies and corresponding simulations agreed with previous findings from batch sorption equilibria and kinetics experiments, where IMD showed one-site kinetic mass transfer between soil surfaces and soil solution. Ideally, sandy soils should be maintained unsaturated by crop irrigation systems and rainfall monitoring during and after soil-drench application. The unsaturated soil will increase IMD retardation factors and residence time for plant uptake, lowering leaching potential from soil layers with low sorption capacity, such as the E horizon. © 2017 Leiva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Simonne E.,University of Florida | Hutchinson C.,University of Florida | DeValerio J.,Bradford County | Hochmuth R.,North Florida Research and Education Center | And 9 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.

Cherry R.,Everglades Research and Education Center | Lu H.,Everglades Research and Education Center | Wright A.,Everglades Research and Education Center | Roberts P.,Southwest Florida Research and Education Center | Luo Y.,Everglades Research and Education Center
Journal of Entomological Science | Year: 2012

Silicate slag was applied to soil of Captiva, Floratam, and Raleigh varieties of St. Augustinegrass to measure the effect of plant silicon on resistance of the varieties to southern chinch bugs, Blissus insularis Barber, and plant disease. In general, silicate slag addition increased Si and Cu content in leaves but tended to decrease P and Mg concentrations. Tissue nutrient contents were generally lowest for Floratam; this trend occurred both with and without silicate slag amendment, indicating a lower nutrient requirement than with other varieties. Chinch bug survival was lowest and development slowest on Captiva which was the only variety with resistance to the insects.There were no significant differences in survival or developmental rates of chinch bugs between silicon treatments within any of the 3 varieties. In disease assessments, Raleigh was more susceptible to gray leaf spot than Captiva or Floratam. However, the addition of Si resulted in significant disease reduction in Raleigh. The addition of Si resulted in disease reduction in Floratam as measured by disease incidence, but not severity. The addition of Si slag caused significant increases in stolon number, stolon length, and leaf blade width in 1 - 2 varieties. Varieties varied in response to Si fertilization among 6 growth characters measured.

Cherry R.,University of Florida | Lu H.,University of Florida | Roberts P.,University of Florida | Roberts P.,Southwest Florida Research and Education Center
Journal of Entomological Science | Year: 2015

The southern chinch bug, Blissus insularis Barber, is the most damaging insect pest of St. Augustinegrass. Numerous studies have shown direct damage to the plant by chinch bugs. However, these studies did not determine if the insect may be causing indirect damage to the plant by making it more susceptible to disease. The study reported herein demonstrates that the fungal plant disease, gray leaf spot (Magnaporthe grisea [T.T. Hebert]), significantly increased in St. Augustinegrass after being infested with chinch bugs. Damage by the insect to other morphological and growth traits is also reported. This study emphasizes the complexity of southern chinch bug damage to St. Augustinegrass by direct damage and by indirect damage making the plant more susceptible to disease.

Dourte D.,University of Florida | Shukla S.,Southwest Florida Research and Education Center | Singh P.,Indian International Crops Research Institute for the Semi Arid Tropics | Haman D.,University of Florida
Journal of Hydrologic Engineering | Year: 2013

Accurate and current rainfall characterization is an important tool for water-related system design and management. Updated rainfall intensity-duration-frequency (IDF) relationships in peninsular India were developed; impacts on runoff and groundwater recharge attributable to changes in rainfall characteristics are discussed. Two data sets were used from gage in Hyderabad city, the capital of Andhra Pradesh: hourly rainfall data for the 19 years from 1993-2011 and daily rainfall data for the 30 years from 1982-2011. Hourly data were used to develop updated rainfall IDF relationships; daily data were used for trend analysis of threshold-based rainfall events. IDF curves were developed for return periods of 2, 5, 10, 15, 25, 50, 75, and 100 years for 1-, 2-, 4-, 8-, and 24-h durations. The updated IDF relationships showed a significant change in rainfall characteristics compared with older relationships for the region surrounding Hyderabad, India; they showed greater rainfall intensities across all durations and return periods. Greater intensity storms may reduce groundwater recharge and increase runoff, making the surface storage of runoff increasingly important to enhance recharge and reduce flooding risks. © 2013 American Society of Civil Engineers.

Kadyampakeni D.M.,Southwest Florida Research and Education Center | Morgan K.T.,Southwest Florida Research and Education Center | Schumann A.W.,University of Florida
Journal of Plant Nutrition | Year: 2016

ABSTRACT: A three-year study was conducted at two sites in Florida with Spodosols and Entisols differing in drainage characteristics to: 1) estimate biomass and nutrient accumulation in 1- to 5-year-old citrus and their relationship to tree size; and 2) determine tree size characteristics as a function of time. Nitrogen (N) accumulation with intensive drip- and microsprinkler fertigation increased by 45% over conventional grower practice (Conventional) at the Spodosol site (SS). Phosphorus (P) and potassium (K) accumulation were similar. The results further showed that intensive fertigation increased citrus growth rate (by up to 330%) in 6 months resulting in greater canopy volumes and trunk cross-sectional areas than conventional practices at the Entisol site. Results at SS showed that canopy size and trunk cross-sectional areas for Conventional were similar to drip fertigation probably because it was fertigated. This suggests the possibility of improving nutrient accumulation and tree size with intensive fertigation practices and a modified, fertigated conventional practice. © 2016 Taylor & Francis Group, LLC.

Kadyampakeni D.M.,Southwest Florida Research and Education Center | Morgan K.T.,Southwest Florida Research and Education Center | Nkedi-Kizza P.,Univserity of Florida | Kasozi G.N.,University of Florida
Journal of Plant Nutrition | Year: 2015

Citrus production in Florida is ranked first in the United States. Success of the citrus industry in the state relies heavily on sound water and nutrient management practices. Recently, citrus production has been declining due to the escalating prevalence of the citrus greening (Liberibacter asiaticus) and canker (Xanthomonas axonopodis) diseases. One option being explored is the manipulation of nutrient management scenarios to increase and enhance tree productivity. The paper presents a review of the management, analytical and application methods of three major nutrients Nitrogen (N), Phosphorus (P), and Potassium (K) on Florida's sandy soils with low organic matter (OM) and high leaching potential due to heavy annual rains (∼1200 mm). The NPK management options for Florida citrus are compared with those of other citrus producing regions around the world. Also, the critical tissue and soil nutrient concentrations for optimal and high citrus production are discussed. The review paper should provide important nutrient management guidelines to citrus growers in Florida and other regions with similar climatic and soil conditions. © 2015, Copyright © Taylor & Francis Group, LLC.

Barkataky S.,Southwest Florida Research and Education Center | Morgan K.T.,Southwest Florida Research and Education Center | Ebel R.C.,Southwest Florida Research and Education Center
Irrigation Science | Year: 2013

Citrus irrigation scheduling is usually based on evapotranspiration (ET) multiplied by a crop coefficient that varies throughout the year. However, ET at 10°C and less has not been investigated. Citrus acclimate to temperatures below 10°C, which affects ET, and therefore may allow irrigation scheduling to be adjusted accordingly. Three separate growth chamber experiments were conducted in complete block design with two temperature treatments and 8-one tree replications with the objective of determining water use of 'Hamlin' orange exposed to cold temperatures. The treatments included: full cold-acclimating temperatures, alternating 10 days cold and 3 days warm temperatures, and alternating 10 days warm and 3 days cold temperatures. Although well-watered, trees exposed to temperatures ≤10°C demonstrated lower water use compared to trees held at temperatures that promoted growth. Reduction of water use of cold-treated plants than the controls was 66, 20-57, and 14-28% during full cold-acclimating temperatures, alternating 10 days cold and 3 days warm, and alternating 10 days warm and 3 days cold temperatures, respectively. Reduced water use of cold-treated plants was due to stomatal closure, increased root resistance, and decreased leaf area. Effective irrigation scheduling based on water requirements as they change during cold-acclimating temperatures should save water while providing adequate water for yield and quality. © 2012 Springer-Verlag.

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