Biological control of Rhizoctonia solani by stimulationof naturally present antagonistic Lysobacter spp.

Abstract: Disease suppressive soils towards Rhizoctonia solani AG2 were found to comprisethree closely related antagonistic species, i.e. Lysobacter antibioticus, L. capsici, andL. gummosus. Isolates of these species showed strong in vitro inhibition of several plantpathogens. The current research focuses on the ecology of these Lysobacter species with the aimto stimulate their natural population in soil and as a consequence enhance diseasesuppressiveness of soil systems. Recent results showed that chitin, chitosan, yeast cells andmushroom powder stimulated Rhizoctonia disease suppression in a bioassay with sugar beet.Meanwhile, Lysobacter populations detected by QPCR were about 5 to 20 times higher than inthe control soil. Other organic compounds such as compost or cellulose were not effective. Withthese results we finally aim to develop a more sustainable growing system, benefitting from themicroflora naturally present in soil.