Influence of water potential on the survival and saprophytic activity of Rhizoctonia solani AG 4 in natural soil

Abstract

The survival of Rhizoctonia solani AG 4 was monitored in a natural Arredondo fine sand incubated under controlled water potentials. In general, survival was greater in soils held at intermediate water potentials of −2 to −15 bars (1 bar = 100 kPa) than in moister or drier soils. Saprophytic colonization of rye stem pieces by R. solani AG 4 in artificially infested, natural soil occurred at five water potentials ranging from −0.05 to −15 bars. Colonization did not occur at −1500 bars. Maximum colonization at any of the former water potentials was detected 1 or 2 days after the beginning of an experiment, but it decreased rapidly after 3 days.