Cotton Stem Blight and Boll Rot

Abstract

Cotton stem blight and boll rot is caused by the necrotrophic fungus Sclerotinia sclerotiorum (Hu et al. 2018). This pathogen can attack hundreds of plant species including many important agricultural crops such as vegetables, legumes, sunflowers, canola, many flowering bedding plants, and stone fruits (Kohn 1979). The disease caused by Sclerotinia spp. is commonly referred to as white mold. The disease is favored by cool temperature (between 59 and 75 degrees Fahrenheit) and moist conditions under a closed plant canopy. S. sclerotiorum is a soil-borne fungus that usually infects the lower stem and other foliage tissues near the soil surface and can attack roots of some plant species. However, the primary impact of white mold on cotton is manifested in yield losses, although cotton stand establishment and seed quality could be affected by this disease. Due to wet and cool weather conditions during the “monsoon” season in the southeast Arizona, fields with a history of bean production will have an increased risk of cotton boll rot and stem blight.