Cotton stem canker in North Carolina caused by Phoma exigua

摘要

Cotton plants exhibiting various symptoms, including death, wilting, black sunken lesions on stems, and terminal necrosis were detected in northeastern North Carolina in mid-June of 1999. Disease incidence varied from less than 1 percent to more than 50 percent in some fields. Microscopic examination of infected stem tissue revealed the presence of the fungus Phoma exigua. Pycnidia and spores of the fungus were abundant in stem and terminal tissues.