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United States Department of Agriculture

Agricultural Research Service


Location: Crops Pathology and Genetics Research

2010 Annual Report

1a. Objectives (from AD-416)
1. Demonstrate alternatives to MB in key crop systems and regions dependent upon MB. This will be accomplished by conducting replicated, large-scale field trials that will compare standard treatments with MB to the best available alternatives. The alternatives will include substitute fumigants and supporting integrated pest management (IPM) practices. The trials will be conducted by multi-disciplinary teams in partnership with commercial growers at field locations that collectively represent the diversity of the commercial production systems. 2. Conduct comprehensive assessments of alternatives to MB in key crop systems and regions dependent upon MB. This will be accomplished by multi-disciplinary collection and analysis of biological, environmental, and economic data from the trials described above. 3. Identify key variables affecting the efficacy of MB alternatives and demonstrate management and predictive use of the variables to optimize performance of the alternatives. 4. Assess and demonstrate emissions reduction technologies and strategies for fumigant alternatives to MB. 5. Conduct multi-regional education programs that instruct growers, farm workers, and associated members of the agricultural community on optimized, IPM-supported use of MB alternatives.

1b. Approach (from AD-416)
The project will achieve its objectives by using a collaborative, inter-disciplinary approach and will include operational, assessment, and educational components. The operational component will involve horticulturists, soil and atmospheric chemists, plant pathologists, nematologists, weed specialists, engineers, economists, extension educators, and regulatory specialists working together with commercial growers, nurserymen, advisors, and other agricultural workers. The teams will demonstrate, assess, and optimize use of MB alternatives in commercial fields. The optimizations will focus on identifying and managing variables that maximize fumigant efficacy and minimize fumigant emissions. Where appropriate, integrated pest management practices will be demonstrated and evaluated for contributions to optimizing MB alternatives. The assessment component of the project will involve advanced analysis of economic, environmental, and social data obtained from the field trials. As information accumulates from activities in the operational and assessment components, it will be extended to end users in the educational component of the project. Educational outreach will be achieved via indoor and outdoor extension meetings, newsletters, educational websites, and peer-reviewed and popular publications. Teams involved in the operational, assessment, and educational components will be drawn from diverse public and private institutions, including, but not limited to: USDA-ARS (Davis, Parlier, Riverside, and Salinas locations, with possible contributions from Corvallis and Wenatchee); University of California, including UC Cooperative Extension; California Environmental Protection Agency; California Department of Food and Agriculture; commercial fumigant applicators and manufacturers; marketing and research boards for horticultural commodities; and producers.

3. Progress Report
Thirteen research & demonstration projects were conducted under the Pacific Area-Wide Program for Integrated Methyl Bromide Alternatives. The projects were designed to facilitate stable transitions to alternatives to soil fumigation with methyl bromide(MB)in: perennial fruit, nut & rose nurseries; raspberry nursery; forest nursery; cut flowers & ornamentals; sweet potato hot bed; almonds & stone fruits; grape; strawberry; and walnut. Each project established three or more research & demonstration trials that focused on fumigant alternatives to MB(e.g., 1,3-dichloropropene [1,3-D], mixtures of 1,3-D+chloropcrin, methyl iodide + chloropicrin, and metam sodium + chloropicrin; drip and shank applied). Efficacy of the alternatives was assessed according to pathogen and weed control and yield of salable products. The sweet potato project completed a trial evaluating combinations of alternative fumigants, pre-emergence herbicides, and fungicides as MB alternatives. The almond/stone fruit project established two new orchard replant trials to test and demonstrate fumigant & non-fumigant alternatives to MB for management of plant parasitic nematodes and replant disease(RD) (biologically mediated growth suppression in absence of significant plant parasitic nematode populations). These trials featured conventional strip and broadcast fumigation treatments as well as “reduced footprint” GPS-controlled spot fumigation treatments. Growth and, where possible, yield assessments were completed for nine almond & peach replant trials. Technology for automated measurement of light interception by tree canopies was tested and applied to assess tree growth & yield potential. The grape project conducted growth & yield assessments for three replant trials established in previous years to evaluate drip and shank-applied fumigants and a mustard crop rotation as MB alternatives. The strawberry project evaluated a “raised-bed trough system” for field production of strawberry fruit. The troughs are lined with mesh that confines strawberry roots to a rooting medium(coir or amended field soil)that is amenable to sanitation. Relatively small amounts of chloropicrin and steam were effective for disinfesting the trough media for reuse over years. Results of previous strawberry trials were summarized & indicated that, in conventional fruiting beds, pre-plant fumigation with 150 to 200 lb/acre of either 1,3-D+chloropicrin followed by metam sodium or Midas under totally impermeable film(TIF)afforded pest control and yields equivalent to those following MB. However, at some sites, low rates of 1,3-D + chloropicrin over successive years has been accompanied by increased incidence of root & crown rots. The walnut project continued a trial examining integration of a nematode-tolerant rootstock and alternative fumigants(1,3-D and 1,3-D + chloropicrin). Rudimentary cost-benefit analyses were completed for MB alternative treatments in the almond & stone fruit and the grape projects. Two projects focused on field management of non-target fumigant emissions were completed. All projects conducted educational outreach at field demonstrations, extension meetings, and scientific conferences.

4. Accomplishments
1. Methyl bromide (MB) alternatives were optimized and demonstrated for production of perennial fruit, nut, and rose nurseries. Annual field production of rose and deciduous tree nursery stock in CA has been valued at more than $165 million (USDA NASS, 2007). Telone II (1,3-D) treatments have been used as an alternative to MB in these nursery sectors, but additional work is needed to improve reliability of the treatments, mitigate their atmospheric emissions, and facilitate their continued commercial adoption. Towards optimizing Telone II reliability and reducing its atmospheric emissions, ARS Researchers in Davis, CA evaluated efficacy of 1) dual-depth injection of Telone II through extended-length, winged shanks; 2) sprinkler-applied water seals, and 3) virtually impermeable film (VIF). It was determined that VIF reduces fumigant emissions while maintaining or improving weed and pathogen control, but sprinkler-applied water seals and extended shanks were less effective. Improved VIF plastic mulch was validated for the nursery stakeholders as an effective tool to maximize performance of Telone II while minimizing its emissions.

2. Effective methyl bromide (MB) alternatives were demonstrated for production of raspberry nursery stock. Raspberry nurseries have relied on pre-plant fumigation with MB to produce approximately 7 million plants annually, which are the basis for an annual fruit crop worth ca. $278 million. ARS Researchers at Davis, CA tested fumigant alternatives to MB, including Inline (1,3-D+chloropicrin formulated for drip application), Telone C35 (1,3-D+chloropicrin, shank-applied), Midas (iodomethane+chloropicrin, shank-applied), and plastic mulch sealing films at an experiment station and three commercial nurseries in CA and WA. Soil solarization also was evaluated, alone and in combination with Inline. Telone C35 (440 lb/acre) and Midas (350 lb/acre) emerged as effective alternatives to MB+chloropirin and matched the MB standard for plant production and pest and pathogen control (weeds, lesion nematode, Agrobacterium tumefaciens [cause of crown gall] and Phytophthora rubi [cause of root rot]). Virtually impermeable film (VIF) generally improved efficacy of the alternative fumigants, compared to standard high density polyethylene, but solarization was not effective. Telone C35, especially in combination with VIF, was validated as an effective MB alternative for raspberry nursery stakeholders, whereas transition from MB to Midas, although technically feasible, may be complicated by uncertain registration status and relatively high material cost.

Last Modified: 2/23/2016
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