See:
Squash (Cucurbita spp.) - Fusarium Crown, Foot, and Fruit Rot
Squash (Cucurbita spp.) - Verticillium Wilt
Cause The fungus, Fusarium oxysporum f. sp. niveum, , which may persist for long periods in the soil as durable spores (chlamydospores) or in association with plant debris. Seed can also transmit Fusarium wilt, usually by contamination of the seed coat.
There is specialization within this fungal species towards various plant hosts affected. These formae speciales of Fusarium oxysporum, which incite Fusarium wilt on cucurbits are as follows: f. sp. benincasae (wax gourd), f. sp. cucumerinum (cucumber), f. sp. lagenariae (bottle gourd), f. sp. luffae (vegetable sponge), f. sp. melonis (melons), f. sp. momordicae (bitter gourd), and f. sp. niveum (watermelon). No formae speciales of Fusarium oxysporum has been reported for squash; however, some varieties of summer squash can be affected by F. oxysporum f. sp. niveum, the wilt strain which affects watermelon. There are also races within the formae speciales; at least three watermelon races, four melon races, and three cucumber races have been reported.
Symptoms Plants may wilt slowly as foliage yellows or may wilt suddenly without yellowing. Wilting is most severe during water stress. In cross-section, the lower stem shows darkened vascular tissue. May be confused with symptoms of Verticillium wilt.
Cultural control
- Avoid fields with a history of wilt.
Chemical control
- Metam sodium has reduced this disease in watermelon in the Hermiston, OR area. Restricted-use pesticide.
Biological control
- Actinovate AG at 3 to 12 oz/A as a soil drench at planting. 4-hr reentry. O
- Bexfond at 7 to 28 fl oz/A. 4-hr reentry. O
- Double Nickel LC at 1 to 2 quarts/A as a banded soil spray or drench on 4- to 6-week intervals or at 0.5 to 4.5 pints/A on 2- to 4-week intervals. 4-hr reentry. O
- Rootshield WP at 3 to 8 oz/100 gal water for greenhouse soil drench and field chemigation or at 16 to 32 oz/A as an in-furrow spray. 4-hr reentry. O
- Stargus at 3 to 4 quarts/A as a soil drench on 10- to 21-day intervals. Preharvest interval is 0 days. 4-hr reentry. O