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United States Department of Agriculture

Agricultural Research Service

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Research Project: Optimization Of “Horn” Phosphine Fumigations To Retain California Walnut Exports

Location: Commodity Protection and Quality Research

Project Number: 5302-43000-037-28-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2013
End Date: Aug 31, 2014

Ensure pest-free security and food safety of walnuts in postharvest marketing channels via the development of efficient, economical, and environmentally benign chemical treatments. Retain and expand export of California-grown walnuts. Collect insecticidal efficacy data using the “Horn” Vaporphos phosphine fumigation system and optimize to specifically address the rapid through-put processing demands of the walnut industry.

Phase 1, year 1 (completed). Evaluate insecticidal efficacy of cold-temperature (< 50 F) “Horn” or “Vaporphos” phosphine (100% purity) and warm-temperature (< 70 F) “Ecofume” phosphine (98.2%, carbon dioxide to phosphine mixture), and index relative to methyl bromide and sulfuryl fluoride at laboratory and pilot scales. Couple with residue analysis. Phase 2, year 2 (completed). Engineer phosphine fumigations to be efficacious on the shortest timescale possible through the integration of physical (e.g., vacuum) and chemical approaches, such as developing fumigant mixtures with other gases. Graduate toward commercial scales and scenarios used by the walnut industry for fumigation; included ~5,000 specimens of the most phosphine-tolerant life stage of dried fruit beetle, navel orangeworm, codling moth, red flour beetle, and warehouse beetle. Phase 3, year 3 (current). Apply what is learned from Phase 1 & 2 and tailor to logistics of commercial walnut harvest and distribution. Disseminate results of this study through local and annual meetings of the California Dried Fruit and Nut Association.

Last Modified: 10/18/2017
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