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United States Department of Agriculture

Agricultural Research Service

Related Topics


Location: Subtropical Plant Pathology Research

2013 Annual Report

1a. Objectives (from AD-416):
To establish the effective rates of a novel, chemical, non-fumigant methyl bromide alternative, establish crop sensitivity to the material, determine optimal application method, and potential worker safety requirements.

1b. Approach (from AD-416):
Research sites in Florida will be established at two locations that have adequate pest pressure to evaluate the spectrum of activity of the experimental material applied under a typical production system for each selected crop. The first two studies to be implemented will be in the raised-bed vegetable and strawberry production system. The strawberry trial will include seven treatments: Untreated Check, four rates of the experimental material, MeBr (as the standard), and the best non-chemical standard developed in a recently completed project. In the vegetable trial, to be conducted at the USDA, ARS Research Farm in Fort Pierce, FL, the experiment will be conducted as split plot design with all treatments consisting of 100’ of treated bed with the split consisting of application method. Treatments will be replicated four times and main plots will be arranged as a randomized complete block design. The MeBr application for the vegetable trial will be shank applied at bed formation. All treatments will be covered with Canslit brand metalized film to assist with whitefly control. In the strawberry trial, to be conducted at the strawberry research farm in Dover, FL experimental treatments will be applied in paired plots with the MeBr treatment. In the second year of the project, both of the previous trials will be repeated. Also in the second year of the project, extension personnel and growers will be invited to field day presentations to share the current progress. Nematode, weed, and fungal populations at each field site and for each year will be assessed prior to treatment, immediately following treatment prior to crop establishment, at mid-season of the crop, and at the initiation of harvest.

3. Progress Report:
This research is related to inhouse project objectives 1. Develop new management strategies for control of pests and pathogens currently or previously controlled by soil fumigants in vegetable and ornamental cropping systems; 2. Integrate cultural, biological, and chemical control tactics into technically feasible pest management programs for soilborne pests and pathogens; and 3. Identify impact of pest management tactics on biological and functional diversity of soil microflora, nematode, and weed populations, their competitive interactions, and effects on crop health and to develop genomic technologies to characterize changes in soil microbial populations in response to pest management tactics and the resulting effects on crop health. A novel combination of organic acids was developed in collaboration between the University of Florida and the USDA, ARS Fort Pierce, FL. The combination, referred to as ‘SPK’ (U.S. Patent Application Serial Number 61/153,485) has shown great potential for controlling soilborne pests including fungi, nematodes, and weeds in laboratory, greenhouse, and field microplot trials. Objectives of the proposed research were to further evaluate efficacy as a methyl bromide alternative in high-value crop production systems currently dependent on soil fumigation; raised-bed strawberry and vegetable production in Florida. Few fumigants are currently available for control of soilborne pests in specialty crops. The recent removal of iodomethane, a promising “drop-in” replacement for methyl bromide, from the U.S. market has left only Telone®, chloropicrin (pic), metam sodium/potassium (metam), and dimethyl disulfide (DMDS, Paladin™). These materials are used in multiple combinations and all face regulatory limitations and are under scrutiny by the EPA based on their potential for by-stander exposure due to heightened concerns related to volatile organic compounds (VOCs). The ultimate goal of the proposed research was to identify a non-fumigant measure for the control of soilborne pests in specialty crops. Two strawberry trials were conducted to compare the experimental material to a chemical standard and to a non-fumigant approach to soilborne pest management. Two vegetable trials were aimed at determining if efficacy could be improved through rate manipulation and application technique. There were no measurable volatile organic compounds (VOCs) produced by the experimental material. The higher rate of the experimental material was more effective for pathogen control than was the low rate. Direct contact with the material is required for control of soilborne pathogens and movement of the experimental material is limited to the movement with water. Soil populations of Fusarium spp. Fusarium oxysporum, and Trichoderma were monitored throughout the trial. Immediately following treatment application, populations of Trichoderma spp., a potentially beneficial fungus, were significantly increased in plots treated with the experimental material and remained high throughout the season. Implication of this finding is extremely important for the use of this material as a methyl bromide replacement in the production of tree liners in the southeast, which require a Trichoderma population to prevent transplant failure. In the vegetable trials, all chemical treatments provided greater root-knot nematode suppression than found in the untreated check. Drip applied treatments were more effective for overall weed control. There were few significant differences found relative to crop yield.

4. Accomplishments

Last Modified: 06/25/2017
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