Individual plants may be affected. The disease may be spread from field to field by wind or water or on infected planting stock or crop debris. Control Verticillium by using clean planting stock of a resistant variety. Also avoid high nitrogen levels. Crown rot or vascular collapse is caused by the soil-borne fungus Phytophthora .
Symptoms usually begin in the upper part of the crown and spread downward.
Youngest leaves wilt suddenly and often turn a bluish green. Wilting spreads quickly throughout the plant, and complete collapse occurs within days. Collapse may be one-sided, depending on the number of crowns infected. Infected plants will often break at the upper part of the crown when lifted from the soil. The crown, when cut lengthwise, appears brown or sometimes rose pink throughout.