CONTROLLING COMMON BEAN WHITE MOULD CAUSED BY Sclerotinia sclerotiorum (Lib.) de Bary

Abstract

Bean white mould caused by Sclerotinia sclerotiorum (Lib.) de Bary is a widespread and destructive disease under protective and open field cultivation in Egypt and worldwide. The vegetative sclerotial fungal structures formed by such pathogen give capability to overwinter between seasons. Different strategies are used efficiently to control the disease and eradicate its causal pathogen. The study was carried out to control the disease under Egyptian conditions. Results revealed that variability in virulence among the tested isolates was correlated with their oxalic acid production. Large white lima cultivar was the most resistant while Cranberry beans was the most susceptible in both detached leaf technique or under field conditions. Among the nine Trichoderma spp. used as biological control agent, T. asperellum inhibited S. sclerotiorum growth in vitro and controlled disease incidence in the field more efficiently. Epidemiological studies also revealed that high soil temperature inhibited sclerotial formation even in presence of high soil moisture while dry soil alleviated the inhibitory effect of high temperature. Sowing the selected resistant cultivars on early September at 50 cm distance with eight days interval period irrigation and organic compost for fertilization gave the most significant control for disease incidence and severity under field conditions.