| Disease | Brief introduction | Leaf Sypmtom | Fruit Symptom |
Early Blight | Early blight can affect the foliage, stems, and fruit of tomatoes. |
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LateBlight | Late blight affects the leaves, stems, and fruit of tomatoes. A strain of late blight is the disease responsible for the Irish Potato Famine. Late blight spreads rapidly. Cool, wet weather encourages the development of the disease. Late blight is caused by the oomycete Phytophthora infestans, which is not a true fungus but still causes devastation to plants. |
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Stemphylium Gray Leaf Spot | Gray leaf spot affects mainly the leaves of tomatoes, starting with the oldest leaves, although it can also infect the stems on the plant.2 It does not infect the fruit, although the disease can be harbored in the seeds of the infected plant. |
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Southern Blight | Southern blight manifests as a white mold growing on the stem near the soil line. In not only affects tomatoes, but it also impacts peppers, beans, cantaloupes, carrots, potatoes, watermelon, and peanuts, among others. |
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Verticillium Wilt | This name can be misleading, as sometimes the leaves will turn yellow, dry up, and never appear to wilt. Verticillium wilt is caused by a soil-borne fungus and can affect many different vegetables. The fungus can persist in the soil for many years, so crop rotation and selection of resistant varieties is crucial. |
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Bacterial Speck | Bacterial speck is one of several bacterial problems that affect tomatoes. Caused by the bacteria Pseudomonas syringae pv. tomato, it reduces yields. There's no cure for the plants once infected. It's most prevalent in cool, moist weather. |
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Blossom End Rot | Blossom end rot is generally attributed to a lack of calcium availability during fruit set. This could be caused by too much high-nitrogen fertilizer or uneven watering, resulting in fluctuations in nutrient availability. It's a physiological disorder, not a disease, but it still results in loss of fruit. |
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Septoria Leaf Spot | Septoria leaf spot is sometimes mistaken for late blight. It's a fungal infection that affects leaves but not the fruit. |
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| Anthracnose | Anthracnose is a very common fungus that causes tomato fruit to rot. |
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