Effects of Crop Management on the Epidemiology of Southern Stem Rot of Peanut

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Abstract
The effects of moisture level, foliar mite and insect infestations, and leafspots on southern stem rot caused in peanut by Sclerotium rolfsii were examined during the summers of 1980, 1981 and 1982. Plants of peanut cv. Florigiant were grown in field microplots (0.8 m in diameter) designed to exclude rainfall from Aug. until digging (low moisture), or in plots that received natural rainfall (high moisture). Plots were sprayed or were not sprayed with an acaricide (dicofol in 1980 and propargite in 1981 and 1982), an insecticide (carbaryl), or a fungicide (chlorothalonil). Fungal inoculum was applied to all treatment combinations at initial densities of 10 or 100 sclerotia/plot. In all 3 yr, mean disease indices were greatest for high moisture + low inoculum plots. Within high moisture + high inoculum plots, treatments with dicofol in 1980 or with chlorothalonil in 1981 and 1982 increased incidence of stem rot. Highest disease incidence in all years was associated with treatments promoting development or maintenance of foliar canopy under the growing conditions of that year.