Melon Pest - Fusarium Wilt (Cantaloupe)
Content from UC IPM: http://www.ipm.ucdavis.edu/
Seedlings may wilt in fields where inoculum is high. More commonly, symptoms are expressed after fruit set and consist of yellowing of a runner on one side of the plant followed rapidly by wilting of the infected runner. Runner lesions develop externally and extend from the crown to the yellowed tips. Other runners collapse in a similar manner and whole plant collapse occurs rapidly. External lesions may develop on roots accompanied by red gumming at or just below the soil surface. Internally, a dark red-brown vascular discoloration extends from roots to runners.
COMMENTS ON THE DISEASE
The pathogen can cause a serious disease of susceptible varieties. It attacks only varieties of Cucumis melo (i.e., melons and muskmelons) and weeds are not considered to be a host. In California, race 2 predominates but race 1 occurs in very limited areas of Merced, Fresno, and King counties. The pathogen survives in soil as chlamydospores, which are thick-walled asexual spores that can survive in soil for over 20 years. The fungux can also sustain istself on the roots of many plants without causeing a disease. The fungus enters plants through roots and disease develops rapidly when soil temperatures are warm.