Location: Crops Pathology and Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
1. Complete long-term growth, yield, pathogen, and economic assessments for methyl bromide alternatives being tested in perennial crop replant trials of the Pacific Area-Wide Program for Integrated Methyl Bromide Alternatives (PAW-MBA). 2. Test use of TIF tarp and a predictive bioassay to reduce amounts of soil fumigants needed for orchard replanting. 3. Contribute summaries of the assessments to PAW-MBA educational outreach efforts.
1b. Approach (from AD-416):
Obj 1. In five almond replant trials, one peach replant trial, and two walnut replant trials testing fumigant and non-fumigant alternatives to pre-plant soil fumigation with methyl bromide (MB), investigators will work collaboratively to collect essential treatment performance data that are required for comprehensive assessment of the alternatives. The fumigant treatments involve different rates and application methods for fumigant alternatives to MB, while the non-fumigant alternatives include spot steam, spot fungicide, and rootstocks that are putatively tolerant to replant problems. All of the treatments are applied in either randomized complete block designs (almond and peach trials and one of the walnut trials) or a latin square design (one of the walnut trials). In treatments of these trials, the data collected annually will include the following: tree survival and trunk circumference, population densities of plant parasitic nematodes, incidence of soilborne disease, percentage of photosynthetically active radiation (PAR) absorbed by the crop canopy, and marketable yield. The marketable yields collected under this agreement and the yields collected in previous years will be individually by year and cumulatively across years. The yield and associated cost data will be subjected to economic cost-benefit analyses. The economic analyses and data on the projected orchard life span (based on measured incidence of soilborne pathogens and crop productivity dynamics) will be used to assess the effectiveness of the fumigant and non-fumigant alternatives to MB. Obj 2. will establish an almond or peach replant trials to 1) test a greenhouse bioassay for prediction of PRD; 2) test and demonstrate efficacy of TIF for facilitating reduced application rates of soil fumigants. For the greenhouse bioassay planned soil will be collected before fumigation at multiple sites in the orchard from 0.5 to 2.0 ft soil depths. The soil will be mixed and amended with sand and then subjected the following treatments: 1) non-treated control, 2) pre-plant pasteurization, 3) pre-plant fumigation (CP, equivalent of 300 to 400 lb/ac). Replicate 0.8-liter pots of soil from each treatment will be planted with sprouting Nemaguard peach seedlings. Growth and health of the seedlings at 6 to 8 weeks after planting will be used to predict the risk of replant disease. Growth and root health data will be tested for correlation with responses to soil fumigation in the orchard. For the tests of TIF tarp (Raven Industries, Inc.), 1,3-D + chloropicrin (CP) (either Pic-Chlor 60 or Telone C35) and non-treated controls will be applied in 5- to 8-ft-wide strips in soil at four rates (540, 270, 135, and 0 lb/treated acre). Subplots in each fumigation treatment will be either covered with 13-ft wide sections of TIF tarp or not covered. Efficacy of the fumigation treatments will be evaluated according to resulting improvement in tree growth, compared to the non-treated control. Obj 3. The investigators will work collaboratively to prepare annual analyses and summaries of the assessments described above.
3. Progress Report:
This Specific Cooperative Agreement (SCA) was established in support of objective 2 of the in-house project, which is to conduct comprehensive assessments of alternatives to methyl bromide (MB) in key crop systems and regions dependent upon MB. The goals of this specific project are to complete long-term growth, yield, pathogen, and economic assessments for methyl bromide alternatives being tested in perennial crop replant trials; test use of totally impermeable film (TIF) tarp and a predictive bioassay to reduce amounts of soil fumigants needed for orchard replanting; and, contribute summaries of the assessments to Pacific Area Wide-Methyl Bromide Alternatives (PAW-MBA) educational outreach efforts. Five almond replant trials, one peach replant trial, and two walnut replant trials were monitored collaboratively to evaluate efficacy of fumigant and non-fumigant alternatives to MB for management of replant problems. The fumigant treatments involved different rates and application methods for fumigant alternatives to MB, while the non-fumigant alternatives included spot steam, spot fungicide, and rootstocks that are putatively tolerant to replant problems. All of the treatments were applied in either randomized complete block designs (almond and peach trials and one of the walnut trials) or a latin square design (one of the walnut trials). Data collected from the replant trials in FY2013 included the following: tree survival and trunk circumference, population densities of plant parasitic nematodes, incidence of soilborne disease, percentage of photosynthetically active radiation (PAR) absorbed by the crop canopy, and, where trees were of sufficient age and grower cooperators allowed (3 almond trials and one peach trial) marketable yield. A new trial testing efficacy of TIF plastic mulch to reduce fumigant emissions and improve fumigant efficacy was established in 2013; efficacy and emissions data collected from this trial are now being analyzed. The project results, which include economic analyses in the case of the almond and stone fruit trials, have documented cost effective alternatives to methyl bromide and demonstrated integrated approaches to reduced fumigant usage. A field demonstration day was held in Merced County in June of 2013 to extend results of almond and peach replant trials to growers and regulatory stakeholders in the California Department of Pesticide Regulation. The event was attended by approximately 50 persons. More formal forms of project outreach included the following in 2013: presentation of the almond, stone fruit, and walnut orchard replant trial results at the Annual Almond Research Conference and a Production Research Advisory Committee for Walnut, and the Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions. Website materials were prepared for the almond and stone fruit project. A manuscript summarizing results of the Almond and Stone Fruit replant trials, entitled “Managing the almond and stone fruit replant disease complex with less soil fumigant”, was submitted to the peer-reviewed journal, "California Agriculture", and accepted.