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United States Department of Agriculture

Agricultural Research Service

Research Project: Long-Term Assessment of Perennial Fruit and Nut Crop Responses to Methyl Bromide Alternatives

Location: Crops Pathology and Genetics Research

2012 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):
Objective 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.

Objective 2. The investigators 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.

Objective 3. The investigators will work collaboratively to prepare annual analyses and summaries of the assessments described above.


3.Progress Report:

This SCA was established in support of objective 2 of the in-house project, which is to conduct comprehensive assessments of alternatives to MB in key crop systems and regions dependent upon MB.

Five almond replant trials, one peach replant trials, and two walnut replant trials were monitored collaboratively to evaluate efficacy of fumigant and non-fumigant alternatives to methyl bromide (MB) for management of replant problems. 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). Data collected in FY2012 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 (almond and peach trials only) marketable yield.

A field demonstration day was held in Merced County in June 1 2012 to extend results of almond and peach replant trials to San Joaquin Valley growers. The event was attended by approximately 140 persons. Results of the walnut replant trials were presented to University of California Farm Advisors in a workgroup field tour in May 2012. More formal presentations of the almond and walnut orchard replant trial results were made at the Annual Almond Research Conference and a Production Research Advisory Committee for Walnut, respectively. Website materials were prepared for the almond and stone fruit project.


Last Modified: 7/28/2014
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