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Disease Control and Pest Management

Injury of Stone Fruits by Preharvest Captan Sprays Followed by Postharvest Treatments. G. A. Chastagner, Graduate Research Assistant, Department of Plant Pathology, University of California, Davis 95616; J. M. Ogawa, Professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 66:924-927. Accepted for publication 15 January 1976. DOI: 10.1094/Phyto-66-924.

A preharvest spray of 50% captan [N-(trichloromethyl-thio)-4-cyclohexene-1,2-dicarboximide] (2.4 g/liter) was applied on Le Grand nectarines; Blenheim and Tilton apricots; Suncrest, Fay Elberta, Carnival, and Halloween peaches. Captan-sprayed and unsprayed fruits (peaches and nectarines) were brushed and treated with benomyl plus Botran^® in wax or with benomyl alone in wax (apricots). Fruit were commercially packed and stored at 0.5 and/or 20 C. Suncrest peaches developed surface streaking ranging from brown to black after 4 days of storage and Le Grand nectarines developed irregular or circular surface discoloration after 7 days. Blenheim apricots field-sprayed with captan 20 days before harvest and treated postharvest with benomyl in wax developed diffused brown surface discoloration after 3 days at 0.5 C and more distinct lesions after 3 days at 20 C. Only the fruit treated with captan and Botran^® and/or benomyl in wax after harvest developed surface discoloration. Laboratory studies on Tilton apricots show that similar discoloration developed only when fruit with a captan residue was brushed; more severe symptoms occurred when brushed fruits were treated with a wax solution or when wax containing captan was applied after brushing. Fay Elberta, Carnival, and Halloween peach fruit did not develop any discoloration regardless of pre- or postharvest treatments.