What Makes a Tomato Rot While Still on the Plant?
Tomato plants thrive in well-drained, slightly acidic soil in a sunny location. Numerous cultivars are available to suit the growing seasons of different regions. According to the University of New Hampshire Cooperative Extension, tomatoes are the most popular backyard vegetable crop in the United States. Tomato plants are susceptible to a variety of diseases that cause their fruit to rot while still on the plant. You can maintain healthy plants if you provide proper growing conditions and learn to recognize the symptoms of disease. Does this Spark an idea?
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Blossom End Rot
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Blossom end rot, which is common in rapidly growing tomato plants, is caused by a calcium deficiency during sudden periods of hot, dry weather. According to the Cornell University Plant Diagnostic Clinic, excessive watering or heavy nitrogen application during early growth may make the plant susceptible to this condition. The first symptom is a dark, expanding lesion on the blossom end of the tomato. Organisms cause a secondary infection, which causes the fruit to rot. Some tomato varieties, including Better Boy and Early Girl, are less susceptible to blossom end rot than other varieties.
Botrytis Blight
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Botrytis blight causes gray mold on the stems and leaves, and rot in the stem end of the tomato. A brown or white spot develops on green fruit, and the fruit becomes mushy while the skin remains intact. The culprit is the Botrytis cinerea fungus, which infects plants during wet and humid springtime weather. The disease is common in humid, poorly ventilated greenhouses. Botrytis fungus overwinters in dead plant tissue and becomes active in the spring. There are no Botrytis-resistant tomato cultivars.
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Timber Rot
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The Sclerotinia sclerotiorum fungus causes timber rot in tomato plants. After the plant begins to flower, water-soaked spots appear on the stem at ground level, at leaf and stem intersections, or at the site of an injury. As the disease progresses, the fruits become watery and mushy. The fungus remains dormant in soil for years and becomes active during cool, wet weather. In the spring, the wind carries the spores, which land on and infect susceptible plants. There are no Sclerotina-resistant cultivars.
Control
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To prevent blossom end rot, maintain a consistent water supply to your tomato plants, and use a low-nitrogen fertilizer. Due to the development of fungicide resistance in Botrytis species, the best control of Botrytis blight is prevention. Remove and destroy Botrytis-infected plant material during dry weather, and remove and destroy plant material at the end of the growing season. To prevent timber rot infection, plant tomatoes in well-drained soil, and rotate with nonsusceptible plants. The Virginia Cooperative Extension recommends the fungicide Benlate for commercial crops.
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References
- University of New Hampshire Cooperative Extension Service: Growing Tomatoes; David Kopsell; September 2000
- Cornell University Plant Disease Diagnostics Clinic: Blossom End Rot Fact Sheet; 1999
- Virginia Cooperative Extension: Timber Rot of Tomato; Mary Ann Hansen; May 2009
- Cornell University Department of Plant Pathology: Botrytis Gray Mold of Greenhouse and Field Tomato; T.A. Zitter; Sept. 1986
- Cornell University Plant Diagnostics Clinic: Botrytis Blight Fact Sheet; 2009
- Photo Credit Tomatenpflanze, tomato plant image by Cornelia Pithart from Fotolia.com
