Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 213 - Weeds Affecting Plants | 5220 - Pesticides (includes herbicides, insecticides, fungicides, etc.) | 1140 - Weed science | 100% |
Weed management is one of the major challenges in Florida's citrus, and vegetable production as the weeds cause a significant impact on crop yield through competition for nutrients, light, and moisture. Growers use a combination of chemical and cultivation methods for an effective weed management. However, use of herbicides is the most adopted method. Soil applied pre-emergence herbicides are an increasingly important tool for control of grasses, sedges and broadleaf weeds in citrus and vegetable production. The length of the time an applied herbicide remain active in soil is called its 'persistence' or 'residual activity, ' and anything that affects the movement or breakdown of herbicides affects their persistence. Herbicides vary in their potential to remain in the soil. Soil and climatic conditions along with the herbicidal properties are among a few factors that determine the duration of herbicide persistence and movement in the soil. Some residual activity of herbicides is desirable during the weed seed germination window, from the perspective of weed suppression. However, it may not be desirable for them to persist and cause negative effects on the crop and the environment. Also, knowing the duration of time that a particular herbicide persists in soil can help growers determine the expected weed control period and application scheduling. Hence, persistence and mobility of the herbicides, as well as their effect on the crop and environment should be investigated before making herbicide recommendations to growers, especially in sandy soils of southwest Florida.
MethodsObjective 1:Lab assays will be performed at the Southwest Florida Research and Education Center (SWFREC) utilizing soil column experiments to understand the behavior of herbicides in different soil types and environmental conditions. Trials will be conducted at the commercial citrus groves to evaluate the mobility of herbicides. Chemical quantification of the herbicides and degradation products from the soil and water samples will be performed using high-performance liquid chromatography in tandem with mass spectrometry (HPLC-MS). Observations on the herbicide impacts on weed dynamics will be recorded periodically to understand the efficacy loss of the herbicide products to leaching and run-off.Objective 2:Field trials will be performed at SWFREC and commercial vegetable production farms to evaluate the herbicide persistence and degradation for bare soils versus soils under plastic mulch. For herbicide behavior in the vegetable plasticulture experiments, dissipation will be measured for different scenarios like seepage versus drip irrigation situations. For herbicide analysis, analytical techniques like HPLC-MS will be used.
Target Audience
The target audience includes commercial citrus and vegetable producers, state and county extension faculty, agrochemical industry representatives, master gardeners, and other researchers interested in weed management and related topics in horticultural production.
Changes / Problems
Nothing Reported
Training & Professional Development
Weed identification education: Established a 'weed garden' at the University of Florida's Southwest Florida Research and Education Center. This garden encompasses various live weed species (35+ weeds) commonly found in southwest Florida. It serves as an instructional and weed identification tool to educate extension agents, students, growers, scouting agents and master gardeners, and the public (Story featured in Citrus Industry Magazine https://bit.ly/2L0sDOi). 'Hands-on' workshop sessions were provided to growers, scouting agents, and master gardeners on weed identification and management techniques. Youth development and education: In conjunction with the iGrow program, outreach sessions were conducted to provide training to vocational and high school students to educate the various aspects of horticulture and weed management. In conjunction with the Future Farmers of America (FFA) program, an outreach session was conducted to provide training to high school students to identify various weed species in citrus production. Herbicide best practice education: Educational sessions were conducted on herbicide classification, mode of action, safe herbicide uses, and proper disposal of herbicides.
Dissemination Streams
The information on herbicide efficacy, persistence, weed management, and related topics are disseminated to growers, and other clientele using field days and demonstrations, one-to-one contact, hard-copy, and web-based electronic extension publications. Established field research trials collectively in citrus and vegetables to show the efficacy of popular and novel herbicides, surfactants, etc. Conducted/participated in field days showing herbicide trial demonstration plots. Aso, seminars, and talks were given at the growers' advisory committee meetingsthat are focal points for driving research and extension needs for growers in the region
Next Reporting Steps
Research efforts to evaluate the efficacy of herbicides on weed control in citrus and vegetable production and the impacts of their persistence on crop health and productivity will be continued in the next reporting period.
Target Audience
The focus of this research effort is directed towards understanding the efficacy and persistence of herbicides for effective and economical weed management in citrus and vegetable production. The target audience includes commercial citrus and vegetable growers, state and county extension faculty, and other researchers with interest in weed management and related topics in citrus and vegetable production.
Changes / Problems
Nothing Reported
Training & Professional Development
The outreach program utilizes information generated from the research program to educate growers and stakeholders on profitable and environmentally sustainable weed management systems for citrus and vegetables grown in southwest Florida. Below is an account of the training and professional activities provided in conjunction with this project: Youth Development: In conjunction with iGrow program, outreach sessions were conducted to provide training to school students to educate the various aspects of horticulture and weed management. Weed identification education: Established a Weed garden in the campus of Southwest Florida REC. This garden encompasses various live weed species commonly found in SW Florida and serves as a demonstration tool to educate growers, scouting agents, Master gardeners etc. Herbicide use safety: A session was conducted at natural and aquatic area management workshop on the disposal and decontamination of herbicide wastes. Herbicide residue analysis and Bioassay - Provided herbicide bioassay testing services and soil residue testing services to growers to determine if the affected soils have herbicide content well below injury threshold to citrus and vegetables. Plant Diagnostic Clinic: Offered weed identification services, including weed and invasive plant ID, herbicide phytotoxicity diagnosis, and herbicide residue management through plant diagnostic clinic at Southwest Florida REC.
Dissemination Streams
The information on herbcide persistence, weed management and related topics are disseminated to growers, and other clienteleusing field days and demonstrations, one-to-one contact, hard-copy and web-based electronic extension publications. 30 grower field visits to answer questions and provide information related to herbicide phytotoxicity, weed identification and weed management. Established 13 field research trials collectively in citrus and vegetables to show the efficacy of popular and novel herbicides, surfactants etc. Conducted / participated in 3 field days showing herbicide trial demonstration plots. Presented at Vegetable growers meeting, Citrus Institute and Tomato Institute that are focal points for driving research and extension needs for growers in the region.
Next Reporting Steps
Research efforts to understand the effects of herbicide persistence on weed control and crop health in citrus and vegetables. Program 1: Maximizing weed control and minimizing the adverse effects of herbicides in vegetable plasticulture production utilizing slow-release carriers. Study Objective: Evaluate the effectiveness of slow-release herbicide carriers (e.g., polymeric hydrogels, agriculture byproducts, etc.) for enhancing weed control and minimizing crop injury in vegetable plasticulture Program 2: Determining the effects of herbicide persistence on health and productivity in Citrus Study Objective(s): Assess the fate of herbicides (e.g., glyphosate) in a citrus production system Study the impacts of herbicides on root growth, pre-mature fruit drop and yield in citrus. Research efforts to evaluate novel and alternate weed management techniques for vegetables and citrus. Program 1: Testing the potential of anhydrous ammonia as an alternative soil fumigant Study Objective Evaluate the prospects of using anhydrous ammonia as an alternative to the combination of fumigant/herbicide on weeds and soil-borne pathogens in tomato. <br><br>
<br>What was accomplished under these goals? Program 1: Research has been focused on evaluating the efficacy of pre-emergent herbicides and their combinations for long-term weed management in citrus. Key findings: Utilizing an optimal rate of the pre-emergent herbicide (e.g, Flumioxazin) or combining two pre-emergent (residual) herbicides (Flumioxazin + Indaziflam) in a single application in citrus provided a greater and more extended duration (up to 5 months) weed control in citrus when compared to a post-emergent herbicide (glyphosate) alone. Impacts: This eliminates the need for frequent post-emergence herbicide (e.g., glyphosate) applications (3 to 4 times per year) to supplement weed control. This will save growers cost of production and application time associated with frequent post-emergence herbicide application. Also, this longer-term weed control due to herbicide synergy will facilitate reduced impact on the environment. About 55% of the 39 grower participants in an outreach program based on this research indicated that they would adopt this suggested herbicide program for weed management in their citrus grove. Program 2: Research has been focused on studying the effectiveness of herbicide additives (e.g., surfactants) for improving the weed control efficacy of post-emergent herbicides in citrus production. Key findings: The surfactants evaluated provided an enhanced control of weeds including broadleaved weeds, grasses, and sedges in the citrus rows. Impacts: Growers can utilize surfactants to increase the spectrum and efficacy of weed control in citrus. The use of surfactants will improve the herbicide use efficiency and will create an economic advantage to growers. Program 3: Research has been focused on investigating the persistence and adverse impacts of herbicides (e.g., glyphosate) on health and yield in citrus. Key findings: The objective of an ongoing research under this program is to establish a crop safe glyphosate application for HLB affected citrus groves under 'glyphosate-reliant' weed management programs. From the preliminary observations, we have learned that fruit detachment force (FDF), the force necessary to produce fruit abscission in trees is affected by post-emergent herbicide glyphosate in a dose-dependent manner. The observed reduction in the FDF suggests an increased chance for fruit drop in HLB infected trees when high rates of glyphosate (e.g., >3.5 lbs. acid equivalent of glyphosate per treated acre) were used for under-tree weed management during the periods of near fruit maturity. Impacts: The project is in its early stage. With confirmation from repeated trial data, the information on crop and yield safe glyphosate dosages can be provided to growers. Also, the long-term goal is to help growers in adopting alternate strategies (e.g., utilizing pre-emergent herbicides) for longer-term weed management beyond traditional glyphosate-reliant programs for assuring good yield from HLB affected citrus by preventing unnatural fruit drop of young fruits. Program 4: Research has been focused on studying the weed control efficacy and environmental fate of pre-emergent herbicides in row-middles in commercial vegetable farming Key findings: The pre-emergent herbicides evaluated demonstrated excellent weed suppression in row-middles in tomato plasticulture production. Impact: Pre-emergent herbicides are excellent tool for the row-middle weed management in plasticulture production. Because of high annual rainfall and sandy soils, leaching, or movement of applied herbicides through the soil profile, is common in Florida soils. When herbicides leach beyond the zone of weed seed germination, they may result in poor weed control. Hence data on long term effectiveness of novel and existing residual herbicides in vegetable row-middles are useful for the growers to formulate an effective herbicide program for their row-middle vegetation management. Program 5: Research has been focused on investigating the negative impacts of non-target herbicide application on yield and productivity in vegetable crops (e.g., tomato) Key findings: Reduction in yield was observed due to herbicide exposure-related fruit deformities. For instance, glyphosate and 2, 4-D drift has been found to cause cat-facing, or misshapen fruit to develop in tomatoes, especially at higher rates. The fruit deformation and reduction in the marketable yield was correlated to the timing of herbicide exposure. Tomato plants exposed in a pre-bloom stage or early growth stage to glyphosate and 2,4-D have foliar damage and significantly lower marketable yields than the plants that had exposure at a mature growth stage. Impacts: The observations from this study will provide tomato producers with information on factors (e.g, growth stage of exposure, rate of exposure) contributing to the fruit deformation and reduction in marketable yield due to herbicide exposure and injury. Fruit deformations (often termed as 'cat-facing' in tomatoes) are a result of physiological stress that encumbers normal fruit development. These deformations may be large scars, cavities at the blossom end, kidney-shaped fruit or other unusual shapes. Insufficient data exist on the cause of fruit deformation, but exposure to herbicides has been considered one of the primary reasons. Program 6: Research has been focused on evaluating the effectiveness of slow release herbicide technology for crop-safe weed suppression in plasticulture vegetable production. Key findings: This preliminary study demonstrated the potential of the 'hydrogel' as slow release carriers for pre-emergent herbicides (e.g, s-metolachlor) in vegetable plasticulture production. The observations show 98% control of nutsedge (Cyperus spp.), two months after application, within the raised beds. Moreover, utilizing hydrogel as career for s-metolachlor provided the much-needed crop safety from herbicide injury to transplants as observed the plant vigor measurements. Impacts: The evaluated technology will benefit vegetable producers who have found that herbicide programs currently available for plastic mulched beds are inadequate for the control of weeds in their locations. The proposed system has the potential to reduce the risk of crop damage, as well as minimize adverse environmental impacts. <br><br><b>Publications</b><br>
Target Audience
The goal of the research program is to ensure that there is a positive impact on farm efficiency and productivity, technology adoption, and enhanced grower knowledge. The target audience includes citrus and vegetable growers, state and county extension faculty, and other researchers with interest in weed management and related topics in citrus and vegetable production
Changes / Problems
Nothing Reported
Training & Professional Development
The outreach program utilizes information generated from the research program to educate growers and stakeholders on profitable and environmentally sustainable weed management systems for citrus and vegetables grown in southwest Florida. Below is an account of the training and professional activities provided in conjunction with this project: Established 5 field research trials collectively in citrus and vegetables to show the efficacy of popular and novel herbicides. Conducted 2 field days showing herbicide trial demonstration plots. Presented at Vegetable growers meeting, Gulf coast citrus growers and Southwest Florida Foundation meeting that are focal points for driving research and extension needs for growers in the region. Youth Development: In conjunction with Future Farmers of America (FFA) program, an outreach session was conducted to provide training to high school students to identify various weed species in citrus production Herbicide use safety: A session was conducted at natural and aquatic area management workshop on the herbicide technology, formulations, modes of action, and herbicides best practices.
Dissemination Streams
Information on herbcide persistence, weed management and related topics are disseminated to growers, and other clientele using field days and demonstrations, one-to-one contact, hard-copy and web-based electronic extension publications.
Next Reporting Steps
Research efforts to understand the effects of herbicide persistence on crop health in vegetable and citrus Program 1: Minimizing the impacts of herbicide injury to vegetable crops utilizing foliar nutrient sprays. Study Objective: Evaluate the effectiveness of nutrient spray applications for minimizing the impacts of herbicide injury and yield loss in pre-bloom and post-bloom stages of the tomato crop. Program 2: Determining the effects of herbicides on fruit drop and yield in Citrus Study Objective: Assess the effects of glyphosate drift and persistence on fruit drop and yield in citrus. <br><br>
<br>What was accomplished under these goals? Research has been focused on evaluating synergistic interaction and long duration weed management prospects by combining or two or more herbicides with residual activity in one application for weed management in citrus production.This eliminates the need for frequent post-emergence herbicide applications (3 to 4 times per year) to supplement weed control. This will save growers cost of production and application time associated with frequent post-emergence herbicide application. Also, this longer-term weed control due to herbicide synergy will facilitate reduced impact on the environment. About 91% of the 34 grower participants in a survey conducted during an outreach program based on this research indicated that they would adopt this suggested herbicide program for weed management in their citrus grove. Research has beeb focused on the herbicidal effectiveness of acetic acid when used as a diluent for the herbicide product Axxe, for row-middle weed management in organic plasticulture systems. Diluting a popular yet expensive organic post-emergent herbicide (Axxe) with vinegar provides comparable weed control in the row-middles of herbs grown under plasticulture systems.Dilution of organic post-emergent herbicide (Axxe) with relatively in-expensive vinegar will enable the growers to use this herbicide below the recommended rate in herbs and will result in a reduction in the cost of production <br><br><b>Publications</b><br>