![]() ![]() ![]() ![]() He was asked to inspect cucumbers on Pohnpei, and found damaged leaves that he thought were gummy stem blight on the stems, Didymella bryoniae, and asked wither it is likely to be the cause of the problem? The farmer has been growing cucumber on the same land for several years. A member from Pohnpei, Federated States of Micronesia, asked for help in identifying a disease of cucumber. ![]() The University of Connecticut, Cooperative Extension System, College of Agriculture and Natural Resources is an equal opportunity program provider and employer.Crops > Vegetables > Cucurbits & others > Cucumber > Cucumber, possibly gummy stem blight, FSMĬrops VegetablesCucurbits & othersCucumber Cucumber, possibly gummy stem blight, FSM Cucumber, possibly gummy stem blight, FSM The Cooperative Extension System does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The recommendations contained are based on the best available knowledge at the time of publication. The information in this document is for educational purposes only. Use in other geographical areas may be inappropriate. This information was developed for conditions in the Northeast. Jude Boucher, IPM, University of Connecticut. Mercure, IPM Program Assistant, University of Connecticut, 1998 Black Rot in Compendium of Cucurbit Diseases. Proceedings of the New England Vegetable and Berry Conference. Gummy Stem Blight in Compendium of Cucurbit Diseases. Avoid chilling injury for the same reason.Control powdery mildew, cucumber beetles, and aphids, as they can predispose plants to black rot.See current recommendations for chemical control measures.A temperature of 44o to 50o F is recommended for storage.If possible, cure pumpkin and squash at 85o F for 2 weeks before storage.Avoid overhead irrigation, especially late in the day when the plants won’t dry before night.Use a crop rotation of at least 2 years, preferably 3 years, away from cucurbits.Pale dots may develop in these spots as well.If the fruit is damaged before or in storage, a brown to pinkish water-soaked area develops and later blackens.Pale dots may develop in the spots when the spots are young.Large irregular areas of the rind become tan to white, and have a ‘petrified’ appearance, with distinct concentric rings.In the center of the spots, pale and dark dots may develop.Later, the rind becomes black and deeply wrinkled.Spots begin as brownish water-soaked areas, which may be large.Under moist conditions, white, cottony fungal growth may appear on the surface.Later, affected areas become blackish and will dry out and shrivel.Occasionally, a gummy ooze appears in the center of the spots, which later dries to a hard deposit.After harvest, the first symptoms are small, dark, round or irregular-shaped, greasy or water-soaked spots anywhere on the fruit surface.On the vine, this disease usually affects immature fruit, causing black decay near the blossom end.If the fruit is sliced open, cutting the spot in half, the rind is dark brown to black directly below the spot, and progressively lighter toward the edges.When humidity is high, a white cottony fungal growth may grow over the spots.The spots may become leathery, the centers become darker, and cracks may radiate from the center of the spots.Under moist conditions, tiny pale and dark dots develop in the center of the spots, although these can be difficult to see.The spots are usually surrounded by a narrow water-soaked area with an irregular border.They remain smooth for a long time, but become depressed as they enlarge.They enlarge slowly, becoming brown to black in the center.Spots start as small, round, dark greenish-tan to black water-soaked areas.There may be tiny pale and/or dark dots in the spots. The spots may have drops of gummy ooze in the center. The spots often start as yellowish, irregular circular areas and later become gray/brown then black. Fruit spots can be small to large, and superficial to deep. This disease was first described in 1891 in France. This fungus also causes the disease known as gummy stem blight on the leaves and stems of watermelon, cucumber, and cantaloupe in more tropical climates, such as the Southeastern U.S. It causes a serious rot on the fruit of winter squash and pumpkin in Connecticut. Black rot is caused by the fungus Didymella bryoniae. ![]()
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