Infections on the roots are known as black dot root rot. If the weather is moist, large numbers of salmon-colored spores can form on the surface of the lesions. Small black specks become visible in the lesions. They start out about half an inch in diameter and turn tan. The primary symptoms are small, slightly sunken, circular lesions on the fruit. The fungus Colletotrichum coccodes easily colonizes lower leaves that are damaged from early blight or flea beetle infestations, and produces spores that spread to the fruit. This disease is such a serious problem in processed tomato products that commercial processors adhere to a strict limit on how many lesions a tomato can have. In tomatoes, it primarily infects fruit on the vine that are ripe or overripe. AnthracnoseĪnthracnose is a very common disease that can infect the leaves, fruit, and flowers of a large variety of plants. You should apply the fungicide four to six weeks before you expect to harvest your tomatoes, so be sure to check the maturation rates for the cultivars you have planted.Īnother application may be required if you will be harvesting your tomatoes in the fall. Planting these at the beginning of the season can give your crops a good head-start, though it is important to note that resistance is not the same thing as immunity – even resistant plants may still be susceptible to infection.Ī fungicide available to home gardeners that is known to be effective against this disease is chlorothalonil, available from Tractor Supply as Bonide Fung-onil Concentrate. Symptoms develop the most quickly when temperatures are above 77☏.Ī number of resistant cultivars are available, including ‘Phoenix’ and ‘Mariana.’ Water in the morning rather than at night, so excess moisture has time to evaporate in the heat of the day. Overhead irrigation, dew, and rain all contribute to its spread.īe sure to always water plants at the soil line to avoid sprinkling the leaves, or use drip irrigation or a soaker hose. The disease is spread by airborne spores, or when infected soil touches the plants. The fungus produces a toxin that causes the tissue between the leaf veins to die and turn dark brown or black.Īnother symptom is concentric rings on green fruit – either when they are still on the plant, or after an early harvest. The main symptoms are cankers – dark brown recessed lesions – on the stems near the soil line, often with concentric rings. Photo by Bruce Watt, University of Maine,, via CC BY-SA. lycopersici, this fungus is closely related to the one that causes early blight, but in addition to attacking the leaves and fruit, it also commonly causes disease on the stems. Alternaria Stem CankerĬaused by Alternaria alternata f. No part of the plant is safe – the roots, stems, leaves, flowers, or fruit, both green and ripe, can all be infected by a number of different types of fungi. Caused by Fungal PathogensĪs is the case with many plants, a wide array of fungi may attack tomato plants. We offer suggested treatments, as well as steps you can take to prevent the same issues in subsequent growing seasons. Others may be fatal, but removing diseased plants from the garden is an important step, to avoid further spread throughout the garden. If you discover a problem, all is not lost! You may still be able to bring in a delicious harvest.īy checking your plants regularly and taking action at the first sign of a problem, many of the diseases and other issues discussed here are treatable, if not curable. Common Tomato Diseases and Physiological Disorders
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