Page Banner

United States Department of Agriculture

Agricultural Research Service


Location: Subtropical Plant Pathology Research

2012 Annual Report

1a. Objectives (from AD-416):
The overall goals of the program will be to establish and implement an areawide pest management research and action program for methyl bromide (MB) alternatives which (a) results from a stakeholder partnership and collaboration dedicated to the demonstration and areawide adoption of methyl bromide alternative technologies; (b)demonstrates the positive impacts and advantages of such a program through enhanced grower profits, reduced worker risks, an enhanced environment, and a proven superiority of wide area adoption; and (c) achieves a mature methyl bromide alternatives system so end-users, consultants and other interested parties will be left with an operation program that will meet the overall goals through its widescale adoption. Overall objectives of the program are to demonstrate and optimize alternatives to MB for management of soilborne pests in the major agricultural production systems currently dependent upon the fumigant. In the targeted production systems, it is expected that the AW project will provide and demonstrate integrated alternatives to MB that: a)contribute to sustained economic competiveness, b) result in reduced, acceptable environmental impacts, and c)increase farm worker safety.

1b. Approach (from AD-416):
1. Demonstrate and evaluate pre-plant alternatives to MB in key crop systems and regions dependent upon the fumigant, particularly by (a) conducting replicated, large-scale field trials focused on MB alternatives in partnership with commercial growers and at locations collectively representing the diversity of the commercial production systems, and (b) In the trials, compare standard treatments with MB to the best available and industry-appropriate alternatives. 2. Collect biological, environmental, chemical, physical, operational, and economic data required for multi-disciplinary assessment of the MB alternatives in each of the key cropping systems and regions; 3. Identify key variables and their critical values responsible for consistent and effective pest control and crop performance with MB alternatives and ultimately use values of the variables prescriptively to adjust and optimize applications of the alternatives; 4. Demonstrate and assess new crop production and emissions management technologies to facilitate acceptance of MB alternatives via demonstrating effectiveness, economic viability and environmentally sound MB alternatives; and 5. Develop and implement regional programs to instruct growers, farm workers, and associated members of the agricultural community on optimized use of MB alternatives.

3. Progress Report:
The Core Advisory Committee met in San Diego, CA on 1 November 2011, in Maitland, FL on 10 February 2012, and in Maitland, FL on 1 May 2012. The Executive Committee met in Maitland FL on 10 February 2012, 1 May 2012, and by conference call on 12 July 2012. Three projects were approved and funded for fiscal year 2012. Two Specific Cooperative Agreements with the University of Florida were amended with additional funding and objectives in the Statement of Work. A new Specific Cooperative Agreement with the University of Tennessee was initiated to evaluate a newly EPA registered biological herbicide for cut flower production.

4. Accomplishments
1. Both iodomethane and dimethyl disulfide can provide good weed, nematode, and disease control in field-grown ornamental crops in Florida. Pest control can be similar to methyl bromide if care is taken with application. Improved application in year 2 in the delphinium trial resulted in higher yields. Use of orifice plates and site glasses increased application uniformity and accuracy among individual chisels delivering these fumigants to soil. A better approach to closing chisel kerfs was also employed in the second year of application. The development of new highly retentive plastics that can be joined for use in broadcast fumigation, combined with Midas and Paladin could provide options for ornamental growers when weeds and nematodes are the principal pest problems, and would allow for the use of lower rates of fumigant while maintaining efficacy. The demonstration trial in cut flowers utilized a virtually impermeable film (VIF) that had to be glued manually at the post rows. The amount of labor that was required to accomplish this was not logistically acceptable. Improvements in this area need to be made and are currently being evaluated by company representatives. The longer period required for plastic removal caused significant issues in the caladium trials, increasing cost of plastic removal and disposal in the second year by 100% due to increased weight from blown sand. Issues related to a lack of commercial application capabilities prevented the caladium grower from utilizing methyl iodide after the completion of the reported trials. Cost estimates for future commercial applications are currently being sought. Although efficacy of methyl iodide was shown, the decision of the registrant to discontinue the sale of this material in the U.S. leaves the cut flower producers will few chemical control options.

2. Results from the Area-wide trials indicate that some soil fumigant alternatives could be used in forest tree nurseries to produce plantable seedlings. The most efficacious alternative fumigants tested were those with higher levels of chloropicrin (i.e. 100% chloropicrin, Pic +®, DMDS + Chlor, Chlor 60). However, the long-term use (multiple rotations) of any MBr alternative may result in unknown pest issues. These trials looked at one rotation; we simply do not know what will happen to soilborne pests after multiple rotations (without MBr). An increase in the use of pesticides will be required to compensate for any MBr alternative short falls, especially for controlling weeds. One item that is known, the final decision in selecting an MBr alternative will vary by nursery. An MBr alternative that works in one nursery may not work in another nursery, which is why managers must be diligent in identifying the best alternative for growing forest tree seedlings in their nursery. Each nursery needs to take into consideration the ability of the soil fumigant to work under individual nursery soil conditions and the impact of the new EPA Reregistration Eligibility Decision (REDs). MBr will eventually be phased out and each nursery needs to identify the best alternative for their nursery in order to continue growing forest tree seedlings.

3. Within Florida strawberry production, many different fumigants were evaluated individually or in combination with herbicides and compared to methyl bromide. Yields of chemical alternatives were averaged across years and locations and compared to the performance of methyl bromide. Strawberry yields were often near equivalent or higher than yieldswith methyl bromide when combinations of fumigants such as methyl iodide, chloropicrin, metam sodium or potassium, 1,3-dichloropropene, and dimethyldisulfide were evaluated. Pest control efficacy for the alternative fumigants was generally less than that of methyl bromide and more highly dependent upon application methods and conditions. Unlike methyl bromide, prevailing soil edaphic and climatic conditions before and after fumigant application were important determinants of efficacy and crop response with the alternative chemicals. It is hypothesized that some inconsistency in pest control is unavoidable with alternatives to methyl bromide. The study demonstrated that applications of various preemergent herbicides are needed to effectively broaden the spectrum of weed control and that improved control of plant parasitic nematodes and crop yields are dependent upon the adoption of early crop destruction as an integrated pest management (IPM) practice.

Last Modified: 07/28/2017
Footer Content Back to Top of Page