Gummy stem blight typically infects plants during periods of high relative humidity and several consecutive days of rain, often from mid/late spring to early summer.
Damage Symptoms:
Circular, brown-to-black spots appear on the leaves.
Stems become affected near their nodes and tend to girdle the plant. A gummy substance exudes from the stem.
Sunken lesions form on the fruit, which rot during storage.
In severe cases, the entire vine may collapse, with the formation of cankers on the stem.
Preventive Measures:
Remove infected plant debris from the field.
Control Measures:
Spray Mancozeb at 2 g/l or chlorothalonil at 2 ml/l.
