How to Manage Pests
UC Pest Management Guidelines
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.
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 fungus can also sustain istself on the roots of many plants without causing a disease. The fungus enters plants through roots and disease develops rapidly when soil temperatures are warm.
Start looking for Fusarium wilt during the vegetative growth stage. Note any infections for management prior to future plantings. Resistance to race 2 is available and should be used in fields with a history of the disease. Most cultivars currently in use in California do not have resistance to race 1. Steam clean equipment after working in an infested field. Rotation out of melons for 5 years will significantly reduce, but not eliminate soil inoculum.
UC IPM Pest Management Guidelines: Cucurbits