Suppression of Rhizoctonia solani and Sclerotium rolfsii diseases in container media containing composted separated cattle manure and composted grape marc

Composts may serve as a substitute for peat as the organic component in container media. Media containing composted grape marc (CGM) or composted separated cattle manure (CSM) were suppressive to diseases caused by Rhizoctonia solani and Sclerotium rolfsii. Radish damping-off severity, as well as disease build-up, were reduced in both CSM or CGM compared with peat. R. solani root rot in pothos was significantly controlled in CGM and CGM-peat mixtures. Both composts were suppressive to disease caused by S. rolfsii in beans and chickpeas. The mechanism of suppression is probably due to the presence of antagonistic microorganisms in the composts, as gamma irradiation of the composts eliminated the suppressive effect. The use of CGM and CSM in container media will provide a high-quality peat substitute suppressive to soil-borne pathogens.