Also, other miticides are not a problem when tank-mixing with Roundup. Field Crop Diseases - Bob Mulrooney, Extension Plant Pathologist. Be on the lookout for charcoal rot. This soil inhabiting fungus can cause problems in short to mid season varieties planted full season. This fungus disease is favored by hot dry weather.
Symptoms usually appear after flowering and during pod fill.
Irregular spots of wilting plants appear in the field. Charcoal rot is primarily a root and basal stem disease, but may be seen on aboveground parts of infected plants. Diseased tissue in the taproot and lower stem develops a grayish discoloration. Eventually the lower stem is girdled, causing wilting and death. The sclerotia resemble a sprinkling of powdered charcoal, hence the name charcoal rot.