Effect of fungicide on disease incidence and yield of bean (Phaseolus vulgaris L.) infected with Isariopsis griseola Sacc. and Ascochyta phaseolorum Sacc.

Abstract

Two foliar diseases of beans, Phaseolus vulgaris L., namely angular leaf spot and ascochyta leaf spot, caused by Isariopsis griseola and Ascochyta phaseolorum, respectively, were effectively controlled with chemicals. Biweekly applications of mancozeb and chlorothalonil (1.12, 2.48 and 4.48 kg/ ha) effectively protected the foliage of bean cultivars Bonita and Naranjito against attacks by both pathogens. Cultivar Bonita responded better to treatments than cv. Naranjito in terms of yield. Some dosages of mancozeb and chlorothalonil increased yield of cv. Bonita affected by angular leaf spot. Yield increases in plots treated with benomyl increased only when the highest rate of this chemical was used. Even at the lowest dosages, the three chemicals tested increased yield in cv. Bonita affected by the ascochyta leaf spot disease.