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Gummy Stem Blight
Causal Agent: (fungus - Didymella bryoniae)
Early
symptoms are round black, wrinkled spots on young leaves and dark sunken areas
on stems. Early infection usually develops from contaminated seed and can be
visible on transplants [Picture]. Often, infected transplants
will have lesions on the the stem [Picture]. On older
leaves in the field, irregular brown to black spots develop between leaf veins
[Picture]. Leaf lesions will expand [Picture],
eventually resulting in the death of leaves [Picture].
As the disease progresses, older stems near the crown, most commonly near a
leaf petiole or tendril, split and a light brown gum oozes from the watersoaked
areas [Picture]. The crown may also be infected and produce
a brown ooze [Picture]. Infected runners die, leaving
fruit exposed [Picture]. vegetables are not usually affected.
Protective fungicide applications are needed for control. Resistance to benomyl
and thiophanate-methyl fungicides have occurred in some growing areas, so these
fungicides are not recommended.