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Sensitivity of Isolates of Sclerotium rolfsii from Peanut in Georgia to Selected Fungicides

The fungicide sensitivity of more than 450 isolates of Sclerotium rolfsii from 11 different peanut fields in Georgia was determined based on percent inhibition of mycelial growth on agar amended with tebuconazole, flutolanil, or PCNB. The 11 locations represented a wide geographic distribution and variety of exposure histories to tebuconazole, flutolanil, and PCNB. Most of the populations sampled were significantly more sensitive than the populations that had the longest exposure to the fungicides. Of the three fungicides tested, tebuconazole and flutolanil demonstrated the strongest positive correlation in 1994 and 1995. The differences in sensitivity among locations suggest that fungicide sensitivity among S. rolfsii populations varies across Georgia. The location with the longest exposure history had the lowest sensitivity to all three fungicides.