SummaryVarious treatment conditions were examined to ascertain an effective utilization method of Coniothyrium minitans. Results were confirmed that a sufficient control effect was achieved at a half dose rate of the currently actual dosage. Considering a treatment timing, a better control effect was obtained by spraying at the time of plowing in residues from the prior crop than by treatment before planting. Moreover, a stable efficacy was obtained by increasing the spray volume applied per unit area to avoid uneven spraying. The results presented above suggest that a stable effect is obtainable by further study of application technique.

Pyriofenone is a new fungicide developed by Ishihara Sangyo Kaisha, Ltd. To determine the fungicidal spectrum of pyriofenone, in vivo pot tests and in vitro mycelial growth-inhibition tests were conducted. Pyriofenone showed excellent activity against wheat and cucumber powdery mildew and moderate efficacy against rice blast in the pot tests. In the mycelial growth-inhibition tests, most fungi were not affected by pyriofenone except for Botrytis cinerea, Helminthosporium sacchari, Pseudocercosporella herpotrichoides, Pyricularia oryzae, Rosellinia necatrix, and Verticillium dahliae. The fungicidal properties of pyriofenone on powdery mildew in cucumber and wheat were evaluated precisely. Pyriofenone exhibited excellent preventive and residual activities. It had high rainfastness in the cucumber leaves against powdery mildew. Pyriofenone also showed inhibitory activity on lesion development upon application until 2 days after inoculation, and the lesion expansion and sporulation of the cucumber powdery mildew fungus were effectively controlled. Furthermore, pyriofenone showed translaminar and vapor activities.

Control of bacterial soft rot in Chinese cabbage by fluazinam SC was evaluated in a vinyl-coated field. Fluazinam solution was applied onto the vinyl-coated field before or after opening the planting oles. Both spray timings enabled to control bacterial soft rot. This application method can be used under the appropriate timing depending on the state of cultivation and can lead labor saving.