The effect of the hyperparasite (Gliocladium virens) on Rhizoctonia solani and on Rhizoctonia root rot of white beans

Abstract

Using light and electron microscopy, Gliocladium virens is proved to be a hyperparasite of Rhizoctonia solani. When hyphae of G. virens come in contact with those of R. solani, the following sequence of events are observed (i) contact of G. virens with host cells, (ii) formation of appresoria, (iii) penetration of host cells, (iv) formation of intracellular hyphae, and (v) collapse and death of host cells. In vitro, G. virens effectively inhibited sclerotial formation of R. solani.Greenhouse tests showed that the presence of G. virens in soil artificially infested with R. solani reduced at planting the severity of Rhizoctonia root rot in white beans. Root rot severity decreased with increasing concentrations of G. virens. A similar result was obtained in soil treated with the two fungi 2 months prior to planting. This study suggests that G. virens may be a promising biological control agent for Rhizoctonia root rot of white beans.