Biocontrol of Dollar Spot Disease by Using Commercial, Antagonistic Microbe Complexes (1) . Outdoor and Field Examination of the Effects

Abstract

Curative, suppressive and protective effects of 3 commercial, antagonistic microbe complexes [Aurace G (abbrebiated as OG below), Active Soiler (AS) . and SS-born (SS) ] on dollar spot disease occurring on turfgrass were examined. These effects were tested using bentgrass grown in sand plots in the university farm and that grown in a nursery of a golf course. The former test is called the outdoor test, while the latter the field test. All the complexes were applied to test plots by spraying almost uniformly by hands. The outdoor test by artificial inoculation porved that all of test complexes had curative, suppressive and protective effects to dollar spot disease. The field test in which naturally-occurring spots were treated with test complexes revealed that their curative effects varied depending on the months of treatment. OG showed relatively fast but short-span curative effects, while AS and SS showed relatively slow but long-span effects. Both outdoor and field tests revealed that all of test complexes had protective effects but that such effects tended to decrease gradually as population density of the pathogen increased in test plots. The outdoor inoculation test gave relatively clearcut results of all effects, while the field test did those of greater variances. Such a difference suggests that the field test using naturally-occurring symptoms may be more reliable than in vitro and artificial inoculation tests to evaluate effects of microbe complexes utilized for biocontrol.