Effects of soil temperatures and inoculum levels of Meloidogyne incognita and Rhizoctonia solani on seedling disease of cotton.
Soreshin of cotton was more severe from combined infections of Rhizoctonia solani and Meloidogyne incognita than from either organism alone, when both critical soil temperature and inoculum concentrations were present. Optimum soil temperatures for disease development from combined infections were 18 and 21 C. Either 2,500 or 5,000 M. incognita larvae per plant, combined with R. solani, increased seedling disease severity over that caused by R. solani alone. When 100 or 500 larvae per plant were added with R. solani, disease severity did not change. Disease severity increased with the highest level of R. solani inoculum either alone or combined with M. incognita.
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United States Department of Agriculture, National Cotton Pathology Research Laboratory, College Station, TX 77840, USA.