Efficacy of metalaxyl for control of rice downy mildew caused by Sclerophthora macrospora Saccardo.

To determine the effectiveness of fungicide Metalaxyl(Ridomil) on rice downy mildew, Cheongcheongbyeo edlings were transplanted in endemic paddy fieid in 1985. Downy mildew symptom begun to appear at 60 days after transplanting and infected tiller increased up to at the end of July. The applications of metalaxyl G. at initial infection period at the rate of 3.0kg (a.i. 150g) per 10a and subsequent metalaxyl 25Wp. spray 10 days later resulted in the most excellent disease control with only infected tillers, control value being and increased grain yield. Two applications of Metalaxyl 25WP. at each corresponding date was o effective, with infected tillers, control value being and increased grain yield by . Such remarkable yield decrease in non-controlled plot was greatly affected by the reduced number of panicles per