Location: Crops Pathology and Genetics Research2013 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. Replacing 0500-00044-021-00D, December, 2011.
3. Progress Report:
In FY2013, research and demonstration activities were continued under subordinate specific cooperative agreements entitled 1) “Demonstration of methyl bromide alternatives plus herbicides for broad-spectrum pest control in open-field nurseries”, 2013 effort focused on: analysis, publication, and popular extension of results from nursery trials conducted previously under the Pacific Area Wide Methy Bromide Alternatives (PAW-MBA); 2) “Integrated Methyl Bromide Alternatives in Walnut Orchards”, focused on: assessment of responses of nematode populations, crop canopy light interception, and yield to methyl bromide (MB) alternative fumigant treatments in two walnut replant trials; 3) “Long-term assessment of perennial fruit and nut crop responses to methyl bromide alternatives”, focused on:  assessment of effects of MB alternative fumigants, crop rotations, and rootstock resistance/tolerance on: nematode populations, crop canopy light interception, almond and stone fruit yields, and overall economic return; and  analysis, publication, and popular extension of results from nine ongoing PAW-MBA trials; 4) “Pacific Area-Wide Pest Management Program for Integrated Methyl Bromide Alternatives- Economic Evaluation”, focused on assisting in economic analysis of fruit and nut and strawberry crop responses to MB alternatives; 5) “Assessment and Management of Emerging Strawberry Pathogens”, focused on tracking and managing Macrophomina and Fusarium populations emergent on strawberry in the absence of MB, 6) “Development and use of metagenomic approaches to address challenging soilborne disease problems in horticultural crops”, focused on metagenomic analysis of soil microbial community responses to soil fumigation and to a potentially pathogen-suppressive compost amendment; and, 7) “Educational Outreach for the Pacific Area-Wide Pest Management Program for Integrated Methyl Bromide Alternatives”, focused on  development of a PAW-MBA website; and  preparation of a special issue of the peer-reviewed journal, "California Agriculture", devoted to results of the PAW-MBA program. In addition, some research and outreach activities were continued for a few of the PAW-MBA program’s earlier projects, which dealt with vineyard replant, cut flowers and ornamental production, and strawberry production.
1. Regulatory benefit from documentation of reduced fumigant emissions under totally impermeable film (TIF). Due to intensive regulation of fumigants as volatile organic compounds (i.e., to meet standards of the US Clean Air Act) and as toxic and potentially carcinogenic substances (i.e., to remove risk due to bystander and long-term regional exposure to the fumigants in air), effective methods are needed to reduce non-target fumigant emissions. Multiple years’ of field research trials, supported in part by the Pacific Area Wide Methyl Bromide Alternatives (PAW-MBA), provided data documenting fumigant emissions reductions achieved by use of TIF for 1,3-D, chloropicrin. Based on critical analysis of the data, the California Department of Pesticide Regulation classified certain 1,3-D application methods and all chloropicrin fumigation methods, all under TIF, as “low emission methods”, and agreed with labels by assigning these methods 60% buffer zone credits (resulting in buffer zones being 60% smaller, compared to higher emission methods). Each of these actions will greatly facilitate effective and efficient use of methyl bromide (MB) alternatives by California growers.
2. Development of practices to manage strawberry pathogens that are emerging with the phaseout of methyl bromide (MB). Field surveys in California have identified Fusarium wilt, caused by F. oxysporum f. sp. fragariae (Fof), and charcoal rot, caused by Macrophomina phaseolina (Mp), as emerging, important soilborne diseases of strawberry. Incidence of these diseases is almost always associated with pre-plant soil fumigation treatments that do not include methyl bromide and that are applied to beds through drip-lines rather than through flat fumigation of an entire field. Twenty-six and nine strawberry breeding lines were evaluated for genetic resistance to Fof and Mp, respectively. Using a disease rating scale of 1 to 5 (1=dead, susceptible plants; 5=healthy, resistant plants), lines tested with Fof had mean scores ranging from 1.1 to 5.0, with 62% of the lines with scores >4.3. Lines inoculated with Mp exhibited scores ranging from 2.0 to 4.5. Fungicide applications controlled neither pathogen, as these findings indicate that continued development and selection of genetic resistance offer an important strategy for managing Fof and Mp on strawberry.
3. Providing analysis, assimilation, and interpretation of Pacific Area Wide-Methyl Bromide Alternatives (PAW-MBA) project results in a permanent, accessible, peer-reviewed format. For optimal impact and credibility to stakeholders, it was decided that results of the PAW-MBA projects should go through a peer review process for publication in a reputable, highly accessible journal. The UC Agricultural and Natural Resources journal, "California Agriculture", was identified as the most appropriate outlet. Seven articles have been prepared and accepted for publication in two special issues of "California Agriculture" dedicated to PAW-MBA results. The accepted articles highlight results and conclusions from PAW-MBA projects on fumigant emissions management and fumigant and non-fumigant methyl bromide alternatives for almond and stone fruits, strawberries, forest nurseries, and perennial fruit, nut and woody ornamental nurseries. The publications will widely increase visibility of the PAW-MBA results to stakeholders and facilitate continued development of methyl bromide alternatives.
Hanson, B.D., Gao, S., Gerik, J.S., Qin, R., Cabera, J.A., Jahala, A.J., Abit, J., Cox, D., Correiar, B., Wang, D., Browne, G.T. 2013. Preplant 1,3-D treatments test well for perennial crop nurseries,but challenges remain. California Agriculture. 67(3):179.