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United States Department of Agriculture

Agricultural Research Service

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Location: Crops Pathology and Genetics Research

Project Number: 0500-00044-030-09-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 17, 2010
End Date: Aug 16, 2015

1) Assess fumigants and rootstocks as Methyl Bromide alternatives in an existing walnut replant trial near Hanford, CA. 2) Establish a walnut replant trial near Chico, CA and prepare for another one near Stockton, CA to assess efficacy of fumigant and non-fumigant Methyl Bromide alternatives. 3) Facilitate economic analysis of walnut replant treatements. 4) Foster adoption and optimization of Methyl Bromide alternatives through educational outreach and exchange with California walnut producers and stakeholders.

Objective 1) On one to two occasions per year, nematode samples will be collected from soil at several spots in each plot. The samples will be collected from 0.5 to 2-ft depth at from each replicate rootstock x fumigation treatment subplot. For each sample, nematode extractions and quantifications will be completed for all nematodes potentially pathogenic to walnut. Each year, during tree dormancy, trunk circumference will be measured for all trees. Each year during the growing season, incidence of crown gall and other soilborne diseases will be determined by visual above-ground inspection. Objective 2) A new walnut replant trial will be established near Chico in Butte County in 2010. The orchard to be replanted will be cleared of trees in summer 2010 and pre-plant treatments will be applied in fall 2010. An attempt to make arrangements for a third walnut replant trial to be established in 2011 in the Stockton area of San Joaquin County. Objective 3) Provide treatment details for use in preparing cost-benefit analyses. Will w estimate walnut yields based on the PAR data collected for each replicate plot. The estimated yields will be used to facilitate the economic assessments. Objective 4) Field days will be organized by the UC Farm Advisors conducting the trials near Hanford, Chico, and Stockton after trees become established. A field day would be held for the Hanford trial in summer 2010, whereas days for the Stockton and Chico-area trials would be held in future years.

Last Modified: 10/17/2017
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