Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Abstract Only
Publication Acceptance Date: 9/25/2005
Publication Date: 10/31/2005
Citation: Johnson, J.A., Valero, K.A. 2005. Vacuum treatments for tree nuts. International Conference on Methyl Bromide Alternatives and Emissions Reductions, October 31-November 3, 2005, San Diego, California. 81-1-81-4. Interpretive Summary:
Technical Abstract: In order to meet consumer demands and export requirements, California tree nuts (walnuts, almonds and pistachios) must be free of insect infestation. Processors have long relied on fumigants such as methyl bromide and phosphine to disinfest their product of field pests such as codling moth and navel orangeworm, as well as storage pests such as Indianmeal moth. Vacuum treatments have been considered as alternatives to chemical fumigation, but required expensive vacuum chambers to obtain the low pressures needed. Recently, inexpensive vacuum treatments were made possible by treating product in flexible, portable containers. We are evaluating vacuum treatments for control of postharvest nut pests. Insect eggs are often found to be the most tolerant of vacuum treatments. Our studies indicate that the response of diapausing larvae is comparable to that of eggs. Of the insects included in our study, navel orangeworm appears to be the most tolerant, particularly the egg stage. Because vacuum treatments are temperature dependent, the utility of this treatment is reduced under cold conditions, when exposures required are too long to be practical. Under warmer conditions, however, effective control may be obtained after relatively short exposure times that are comparable to phosphine fumigation, particularly since no aeration is needed after treatment. Cost of the method is limited to capital expense for the flexible containers and vacuum pump, electrical power and labor costs.