South Florida Pest and Disease Hotline: Gummy Stem Blight Concerns

Web AdminCucurbits, Disease, Florida

Gummy Stem Blight
Photo courtesy of South Florida Pest and Disease Hotline

Gummy stem blight disease has increased in recent weeks in cucurbit fields across southwest Florida, according to the South Florida Pest and Disease Hotline. It has become the predominate disease in some watermelon fields in the area.

The disease remains moderate in cucumber crops on the east coast.

Gummy stem blight’s symptoms appear as light to dark brown circular spots on the leaves or as brown to black, lesions on the stems. There is wilting of the vine, which can be followed by death of young plants. Stem lesions grow in size and slowly girdle the main stem resulting in a red-brown-black canker that cracks and may exude a red to amber gummy substance. Vine wilting is usually a late symptom.

The disease is most problematic in wet years since moisture is necessary for spores to germinate. 

Growers need to be mindful that fungicide programs should be implemented prior to the first sign of the disease. Multiple applications of fungicides are necessary to control gummy stem blight. 

In south Florida, the spray program should be initiated soon after emergence. In other areas of the state, fungicide spray programs can be initiated when the vines begin to “run.” Fungicides like mancozeb or Bravo in rotation will provide good protection before the disease is established in the field.

Source: South Florida Pest and Disease Hotline