Biological Control of Rhizoctonia Stem Canker and Black Scurf of Potato

Publisher Website
Google Scholar
Abstract
The efficacy of several fungal antagonists for control of Rhizoctonia solani on potato was evaluated in greenhouse and field tests. Fermentor biomass (FB) preparations of Trichoderma viride (T-1-R9) and Gliocladium virens (G1-21) applied as dusts to seed potatoes infested with sclerotia of R. solani before planting, reduced disease incidence in the field by 50 and 55%, respectively. Viability of sclerotia from seed pieces retrieved from the field was reduced 54-89% by specific antagonists. In the greenhouse, up to 88% reduction in germination ofsclerotia was obtained by treating sclerotia-infested tubers with FB of T-1-R9 before planting. FB preparations of T. viride (T-1-R9), T. harzianum (WT-6), T. hamatum (Tri-4) and G. virens (G1-21) added to the soil in a mixture of pulverized pyrophyllite (anhydrous aluminum silicate), significantly reduced numbers of propagules of R. solani. After 4 wk, populations of R. solani were eliminated in soils infested with FB of Tri-4. Population levels of the antagonists increased 1000-fold within 4 wk. Sclerotia of R. solani retrieved from antagonist-amended soils were heavily colonized by the antagonists. The variability of colonized sclerotia was reduced 13-100%. Results suggest that both soilborne and tuberborne propagules of R. solani can be effectively reduced by biological means.