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Results of Three Years of Spraying with Fungicide-Insecticide Combinations Against Inflorescence Dieback Disease of Cashew. O. A. Olunloyo, Plant Pathologist, Cocoa Research Institute of Nigeria, P.M.B. 5244, Ibadan. Plant Dis. 67:1319-1320. Accepted for publication 30 March 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1319.

A 19761979 study in Nigeria of the efficacy of chemical protection against inflorescence dieback disease of cashew, caused by Lasiodiplodia theobromae, a parasite of insect-infested tissues, showed that 1.5 g a.i./L of captafol plus 1 g a.i./L of emulsifiable concentrate of gamma-BHC was most effective in preventing inflorescence infection and increasing nut yield per tree. Treatments were 0.5, 0.75, 1, or 1.5 g a.i./L of captafol alone, 0.5 or 1 g a.i./L of gamma-BHC alone, or each amount of each chemical combined with each amount of the other. Nut yield of untreated control trees declined in the first and second years of the study by 18 and 20%, respectively, whereas yield of treated trees increased by 86 and 137%. Yield in treated trees in the third year increased by only 27%, owing to invasion of developing nuts by a complex of fungi. During the 3 yr, trees sprayed with 1.5 g/L of captafol and 1 g/L of gamma-BHC had yields 374, 984, and 1,608% greater than those of control trees. Efficacy of captafol was reduced when 1 g/L of gamma-BHC was added to 1 g/L of the fungicide.