Protecting Raisins Against Insects During Drying and Storage with Malathion-Treated Trays

Excerpts from the report: The use of malathion-treated trays for protecting grapes against insects while drying was first explored by personnel of the American Cyanamid Co. , Fresno County Extension Service, and the Raisin Advisory Board. The treatment appeared very promising because it employed an insecticide with very low mammalian toxicity, and it was a method that would not interfere with the normal processing of the crop. Tolerances of 8 p.p.m. of malathion have been approved and established by the Food and Drug Administration for most of the fresh fruits, including grapes, and many of the leafy vegetables that are eaten raw. These tolerances apply to malathion residues obtained from preharvest treatments. The tests described in this report are a followup of the one mentioned above. The objective was expanded to include not only the evaluation of the effectiveness of treatment in preventing insect infestation of the raisins while drying, but also the effectiveness of the residual deposit in protecting the raisins against damage during storage. The aim was to develop one single treatment to protect raisins from the time they are picked as grapes and placed on the drying trays to the time they are brought to the plants to be cleaned, processed, and packaged.