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United States Department of Agriculture

Agricultural Research Service

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Research Project: An ARS Areawide Pest Management(AWPM) Program for Methyl Bromide Alternatives

Location: Crops Pathology and Genetics Research

2012 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:
Research and outreach projects were continued under the Pacific Area-Wide Program for Integrated Methyl Bromide (MB) Alternatives. The perennial nursery project completed two pre- and post-plant herbicide trials in plots fumigated with MB alternatives at commercial nurseries. The weed control treatments were designed to augment weed control that tends to be insufficient in plots treated with MB alternatives alone. Incremental application rates of 1,3-dichloropropene + chloropicrin (1,3-D + CP)and iodomethane fumigants were demonstrated for cut flowers and ornamentals in a commercial bulb growing operation. The sweet potato hotbed project concluded six grower trials demonstrating solarization, chloropicrin (CP) (under “totally impermeable film”) and metam sodium as MB alternatives; the treatments were demonstrated in combinations with pre-emergence herbicide treatments designed to augment their efficacy. The almond/stone fruit project established a new orchard replant trial to test and demonstrate MB-alternative fumigants (spot, strip, broadcast applcations) and non-fumigant alternatives (spot steam) alternatives for control of replant disease (RD) and plant parasitic nematodes. Also seven previously established almond and peach replant trials were continued and assessed yields, canopy light interception, and nematode populations. The grape project conducted growth and yield assessments for three previously established replant trials testing pre-plant drip and shank-applied fumigant alternatives to MB and a mustard crop rotation for control of nematodes and stimulating crop productivity. The strawberry project demonstrated a “raised-bed trough system” for field production of strawberry fruit without fumigation. The walnut project assessed tree growth and nematode populations in response to different walnut rootstocks and pre-plant fumigant alternatives to MB in trials in the San Joaquin and Sacramento Valleys. Cost-benefit analyses were completed for MB alternative treatments in the almond and stone fruit and grape projects, strawberry project, and the sweet potato project. A fumigant emission trial was completed to quantify reduction in non-target fumigant emissions and improvement in soilborne pathogen control achieved using “totally impermeable film”, compared to standard high-density polyethylene plastic mulch. All projects above, as well as the raspberry nursery project, conducted educational outreach at field demonstrations, extension meetings, and scientific conferences.

4. Accomplishments
1. Methyl bromide (MB) alternatives for sweet potato hotbeds. Sweet potato hotbed production has historically relied on pre-plant soil fumigation with MB, but due to the MB phaseout, hotbed production practices not reliant on MB are needed. Four years of research and demonstration trials were completed in Merced County, California, to test and demonstrate combinations of 1,3-D, CP, and metam sodium with herbicides as MB replacements. Data from the repeated trials indicated that MB is not necessary for sweetpotato hotbeds in California, and that weed control can be obtained by judicious use of fumigation alternatives such as Telone, metam, or the combination thereof, or no fumigants at all when herbicides are used. Because of the cost and limited availability of MB after 2011, growers are rapidly adopting many of the alternatives tested in the project.

2. Long-term assessment of Methyl bromide (MB) alternatives for control of replant disease in almonds and stone fruits. Pre-plant soil fumigation is essential for economical production of many fruit and nut crops, valued at over 12 billion dollars annually in the Central Valley of California alone, and MB, a fumigant of choice, was banned. Yield data were needed to validate alternatives to MB for almonds and stone fruits. Yield assessments were completed for 4 to 6 years (range among trials) in four almond and peach replant trials testing and demonstrating spot, strip, drip, and broadcast treatments with MB alternative fumigants for control of the replant disease (a wide-spread and ill-defined growth and yield suppression induced by crop specific soil microorganisms). All fumigation treatments tested improved yields compared to the control, but treatments with 1,3-D, CP, and combinations of the two fumigants provided equivalent and in many cases superior cumulative yields, compared to the MB standard. Furthermore, the yield data indicated that as little as 10% of the orchard area could be fumigated with CP or CP+1,3-D (conventionally, 50 to 100% of orchard area is fumigated)with resulting adequate growth and yield improvement in the crop. These findings afford grower confidence in MB alternatives and suggest current and future technologies to support productivity in replanted almond and peach orchards with minimal fumigant use.

3. Formal educational outreach with MB alternatives. Varied forms of educational outreach are needed to foster informed use of MB alternatives among nurserymen, almond, grape, peach, strawberry, and walnut growers. Also, for informed decisions, regulatory scientists and other stakeholders need access to crop performance and fumigant emissions data generated by UC and ARS scientists. To address these needs, a website and a special issue of the journal “California Agriculture” devoted to the Pacific Areawide Program for Integrated Methyl Bromide Alternatives (PAW-MBA) were launched. Although neither project is completed, both have been established for peer and public review and further improvement. At this stage, the review process will foster critical assessment of PAW-MBA accomplishments and educational and technical stakeholder needs that remain for the program to address in its final phase. When completed, the website and special issue will foster interactive and long-lasting educational outreach for the PAW-MBA program.

Last Modified: 07/25/2017
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