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Poster: Biology & Disease Mgmt: Chemical Control


Sensitivity of Sclerotinia sclerotiorum to iprodione and propiconazole in Bangladesh
M. ISLAM (1), C. Vrisman (1), S. Miller (1) (1) The Ohio State University, U.S.A.

Sclerotinia sclerotiorum is a destructive plant pathogen causing white mold of mustard. The pathogen was first reported in Bangladesh in 2007. Iprodione and propiconazole have been used to control the disease, but the sensitivity of S. sclerotiorum isolates to these fungicides in Bangladesh has not been determined. One hundred eighteen S. sclerotiorum isolates from Bangladesh and six from Ohio were tested for sensitivity to the two fungicides. Isolates were collected from infected mustard, soybean and cauliflower plants, plated on Potato Dextrose Agar medium (PDA) and purified by mycelial tip culture. Five-millimeter mycelial discs from 2-day-old cultures were plated on non-amended PDA or PDA amended with iprodione (0.0001, 0.001, 0.01, 0.1, 0.3, 1.0 or 10.0 ppm) or propiconazole (0.001, 0.01, 0.1, 0.3, 1.0, 10.0 or 100.0 ppm). Cultures were incubated at room temperature and radial mycelial growth was measured after 48 hours of incubation. EC50 (50% mycelial growth inhibition) values were calculated by regression of mycelial growth relative to the control against log10 fungicide concentrations. EC50 values for iprodione and propiconazole ranged from 0.11 to 0.55 and 0.12 to 0.78 ppm respectively. Since S. sclerotiorum has appeared recently in Bangladesh and fungicide use has been relatively infrequent, these values will serve as baseline data for monitoring their efficacy going forward.