Mycosphaerella melonis (Didymella bryoniae)
A common disease on all cucurbits. Leaf symptoms appear as circular tan to black spots that give the leaves a “scorched” appearance. Stem symptoms are easily recognized as light tan necrotic areas that appear to ooze a clear to brownish sap, gum, or resin from which the disease gets its name. Fruit develop watersoaked lesions, that eventually turn brown and ooze a sticky sap.
The fungus survives from season to season on crop residue and weeds in the field border. Crop rotation is advisable. A preventative fungicide program is required. Overhead irrigation increases the problem. Soil sterilization may be needed in greenhouse situations.
See also The Texas Plant Disease Handbook.
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Publication Revised July 2009