Abstract
Tomatoes were cultivated in soil infected with Verticillium dahliae to which five kinds of microbial materials were applied during the three year period from 1986 to 1988. In all the materials, since the disease incidence and severity of Verticillium wilt were reduced, the yield increased. The microbial population in soil tended to be higher in the plot with application of all the materials than in the no-application plot. It is possible that the high population of microbes hindered the infection of the pathogen and reduced the severity of the disease. On the other hand, since the number of microsclerotia in soil decreased after the application of the materials, it was assumed that antagonistic microbes multiplied. Soil pH showed slight changes. Two materials which increased the content of NH_4-N, generally reduced severity of Verticillium wilt seven to fourteen days after application, but the effect of it could not be confirmed.
