Changes of microflora in turfs soil (Part 2) Effect of the soil conditioner on growth of zoysia grass and control of Rhizoctonia patch

Abstract

The effects of a soil conditioner containing vinegar (acetic acid), chitosan hydrolyzates and extract of alfalfa leaves on the growth of zoysia grass and control of Rhizoctonia patch were studied.
Dry root weight of zoysia grass treated with the soil conditioner was 16-32% more than that of non-treated grass, and the treated grass emerged earlier than non-treated grass inspring. Additionally, in the soil treated with the soil conditioner, the number of effective microbes such as chitinase-producing bacteria including actinomycetes and fluorescent pseudomonads increased and the number ofRhizoctoniameasured by ELISA system decreased significantly as compared with non-treated soil. Consequently, occurrence of Rhizoctonia patch was restricted by application of the soil conditioner.
Five strains were isoleted from the pach. The isolates were identified asRhizoctonia solani [AG-2-2, IV] and could not be repressed by the soil conditioner when diluted for application. Thus, the effectivity for controlling theRhizoctoniapatch would seem to be indirectly promoted by increases of chitinase-producing bacteria including actinomycetes and fluores-cent pseudomonads, which were produced by the application of the soil conditioner.