Gummy stem blight is caused by the fungal pathogen Didymella bryoniae. Any reference to commercial products, trade or brand names is for information only no endorsement is intended.Gummy stem blight is a common disease of cucurbits worldwide, and in northern states has been prevalent on squashes and pumpkins. Please Note: The specific directions on pesticide labels must be adhered to - they supersede these recommendations, if there is a conflict. Promptly incorporate plant debris after harvest. Optimum storage conditions are 55 (52-61) F and 60 (55-75) % RH. Before storing winter squash, harden the rind by curing at about 77 F for 1 – 2 weeks. Avoid injuries to fruit which enable the pathogen to infect. Therefore it is important to have current information about resistance occurrence when selecting fungicides. The pathogen has demonstrated ability to develop resistance to fungicides, including those in FRAC code 1 and 11, plus some in FRAC code 3 and 7 (Endura and Pristine). Select targeted fungicides when the disease has been confirmed present in a crop. Apply fungicides on a preventive schedule. Rotate out of fields where cucurbit crops were grown previously for at least 2 years (4 years recommended after a confirmed occurrence). ![]() Avoid planting multiple cucurbit crops together. This is important when growing transplants and also in the field where preferred drip irrigation is not feasible. Water in the morning when leaves are dry and conditions facilitate fast drying. Keep humidity in greenhouse below 80% with ventilation. When growing transplants, provide separation when possible, such as alternating rows with trays of cucurbits with trays of other vegetables to minimize opportunity for spread. Disease development and pathogen spread is a concern when growing transplants, especially melons due to susceptibility of seedling tissue, favorability of conditions in greenhouses, and increased opportunity for pathogen spread due to close proximity of seedlings. ![]() There are a very few resistant melon varieties, mostly watermelon. Management: Purchase seed that has been tested for the pathogen and fungicide treated. Black decay can develop on cucumber before harvest but more commonly during transit or storage. Tan to brown discoloration occurs on cantaloupe fruit and the netting does not develop completely and is disintegrated. On pumpkin and winter squash symptoms are brown to pinkish and water-soaked at first, then become black, except affected tissue on butternut squash develops white to orange-brown concentric rings. They are visible in the second photograph below which is a close up of leaf tissue.īlack rot is the disease name used when symptoms develop on fruit. Tiny black specks, which are the pathogen’s fruiting bodies, develop on infected plant tissue including fruit. Petiole and stem tissue affected on older plants is water-soaked, tan, and develops a characteristic reddish brown gummy exudate. When seedling stems are infected the tissue often appears water-soaked and can lead to girdling which kills the plant. They can rapidly enlarge becoming irregular. Leaf spots initially are round or triangular when beginning at the leaf margin. Gummy stem blight is the disease name used when symptoms develop on stems and leaves. Fruit rot is most common in pumpkin and winter squashes. Melons are more susceptible to stem cankers than other cucurbits while stems of butternut and related squashes ( Cucurbita moschata) are resistant. Butternut squash and summer squashes are least susceptible. Leaves including cotyledons of all melons are especially susceptible while those of cucumber and some squashes are initially resistant and become susceptible as they age. The pathogen’s previous name was Didymella bryoniae.Īll cucurbit crops are susceptible. Three species of Stagonosporopsis cause this disease. Its spores are moved by splashing water and wind. states, as well as in subtropical and tropical areas of the world. This disease is more common in humid southern U.S. ![]() ![]() Infection occurs when warm (64-82 C), with 75-77 being optimal. Frequent rain and overhead irrigation done when foliage won’t dry promptly (such as when irrigation ends after sunset) promote disease development. Most important is high humidity and plant tissue (in particular leaves) staying wet for at least an hour for infection, longer for lesion development. This disease has been observed sporadically and uncommonly on Long Island, likely reflecting the pathogen, a fungus, not being established and surviving in the area rather than conditions not being favorable.
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