[A simulation study on the yield losses assessment of corn caused by downy mildew disease (Peronosclerospora maydis (Rac) Shaw)]
1988
Sudjono, M.S. | Sopandi, Y. (Balai Penelitian Tanaman Pangan Bogor (Indonesia))
A simulation study on the yield losses assessment of corn caused by downy mildew disease (Peronosclerospora maydis (Rac.) Shaw) had been conducted at Cikeumeuh experimental farm (Bogor) in wet season 1985/86. Seeds of susceptible Metro variety were treated with Ridomil 35 SD, a systemic fungicide which contains metalaxyl active ingredient, for disease intensities control. The seed treatments were at the dosage rates of 0, 0.05, 0.10, 0.15, and 0.20 grams formulation per kg of seeds. Regression analysis between the fungicide applications and downy mildew intensities indicated an exponential function with highly significant coefficient correlation (r = 0,91). From the regression equation it can be calculated that the control of downy mildew will be effective at the rate of 2g/kg of seed in which downy mildew infestation was 60 percent. Disease intensities increased by time from 2 to 8 weeks after sowing, but disease intensity was significantly different between the treated and untreated ones. The disease appeared earlier at a rate below 0,10 g/kg of treated seed as compared to the dosage ones. Regression analysis between yield losses and disease intensities indicated a negative linear equation with highly significant coefficient correlation (r= -0,98). Maximum yield of Metro variety can be achieved at 1,445 t/ha based on the equation when is fully controlled downy mildew (Author's abstract)
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