Abstract: Pencycuron is a novel fungicide of phenylurea type.The Fungicide spectrum of pencycuron in vitro showed that the cam pound had specific antibiotic activity to Rhizoctonia solani,particularly to pellicularia Sasakii.Pencycuron also displayed a strong inhibitory effect on the psasakii mycelial development on agar plate amended with the compound at low concentrations,and induced its morphological disorder in mycelial development.The effect property is almost the same as that of Validamycin.The result shown in glass-house test indicates that the in hibitory effect of Pencycuron on hypha infection is remarkably better than that of validamycin,but the inhibitory effect on the development of lesion is weaker than Validamycin.Pencycuron has remarkably stable persistency in preventing the infection of rice sheath blight its effect lasting more than 35 days,while Validamycin,less than 14 days.Therefore,Pencycuron is a protective fungicide with stadle persistency.The efficacy was affected obviously,when the rice plants in the glass-house wece showered with artificial rainfall at a level of 2pmm 50min after the chemical treatment,The result of field tests is the same as that of the glasshouse.

Key words: Rice sheath blight, Fangicide