If levels of Fusarium are high, seedlings may wilt. More commonly, however, Fusarium wilt symptoms occur after fruit set and consist of yellowing and wilting of a runner on one side of the plant. Lesions on the runner extend from the crown to the runner tip. Other runners soon collapse and the plant dies. External lesions may develop on roots accompanied by red gumming at or just below the soil surface. Internally a dark vascular discoloration may occur.
Solutions
Use resistant cultivars, noting however, that high inoculum levels can overcome the resistance. To reduce the inoculum load, it is necessary to rotate out of watermelon for 5 - 6 years because the fungus may reproduce on resistant watermelons even if there are no wilt symptoms.
