5 Most Common Tomato Diseases

Tomato crop, when grown properly and disease free can produce vibrant, delicious, and healthy tomatoes.
However, there are common fungal diseases known to inhabit the gardens of those tomato growers and inhibit crop production. This article will outline these diseases and discuss, prevention, and treatments for the diseases as to assist the outside tomato grower with crop management.

According to Iowa State Department of Plant Pathology, the most common disease that effects the leaves (foliage) of tomato's is Septoria Leaf Spot. It is characterized by small circular spots that have a light grayish center. Black spotting in the middle of the gray spots is symptomatic of this disease and is actually fungal spores. It is spread by splashing water transferring the spores from leaf to leaf. Typically this disease occurs once the plant begins producing fruit and begins at the base leaves and works its way to the top leaves. This fungal disease lies dormant in plant debris during the winter months, only to resurface itself again during seasoning. There are several ways to prevent Septoria Leaf Spot. When planting or transplanting tomato plants, be sure that they are set an adequate distance apart. This is to ensure that the leaves can easily dry, to prevent spores from being transferred from one plant to another from splashing water, and that it is easier to water at the base of the plant. Watering at the base of the plant assists in ensuring the foliage dries quickly. Rotating the tomato crop and clearing away plant debris is another prevention method to ensure that the fungus, which lies dormant in plant debris during the winter, does not get a chance to infect a new crop. When prevention methods are ineffective, there are various fungicides that can be used to treat Septoria Leaf Spot. Your local home and garden store would be able to assist you in locating the right fungicide for your crop.

Early Blight is evident when brown and black spots appear on the younger leaves of the tomato plant. Unlike Septoria Leaf Spot, it effects the actual fruit and results in premature loss of the flower leaves. When Early Blight begins attacking the crop, the stem area on the fruit becomes sunken in and can turn black. Just as with many fungal diseases, Early Blight thrives in warm and wet weather. Because it also occurs in potato crop, Iowa State's Department of Plant and Pathology insists that one must avoid planting with potato's or in the same soil that potato crop was recently planted in. In addition to prevent the fruit from being infected, it should not be allowed to over-ripen and picked when ready. There are some tomato varieties that are resistant to Early Blight such as Pride, Gold, and Belle, to name a few. Just as with Septoria Leaf Spot, rotation of crop, cleaning up plant debris, and ensuring plant leaves are not wet too long are effective prevention methods for Early Blight. Various chemicals are available to control this fungal nuisance.

Unlike Early Blight, Late Blight thrives in cool, rainy weather. The older leaves are effected first and it produces brown and black spots in the tomatoes. Late Blight is usually seen around mid to late August when there are cooler night temperatures. The morning dew leaves a nice cool and wet playground for this fungal culprit. When fruit is infected, it gives off a bad smelling odor. Prevention and treatment are just the same as Early Blight and Septoria Leaf Spot, including avoiding rotation with potato crop.

Anthracnose is a disease that attacks the fruit. It is characterized by small indents on the fruit that eventually develop dark centers with pink spots. Just as with other fungal diseases, Anthracnose thrives in warm and wet weather and the spores are spread through splashes of rain. Because Anthracnose is most common in overripe fruits so to prevent this disease from effecting the crop, one must harvest immediately. As with many fungal diseases, it lies dormant in plant debris during the winter months, so soil rotation and effective clean up of old plants and foliage should take place.

Wilt is another common disease in tomato's. Tomato crops with Verticillum Wilt are able to survive but have stunted growth and do not produce as many tomatoes as healthy plants. This disease effects the stem. It can be detected by the yellowing and wilting of leaves that start at the bottom of the plant and progressively moves upward. Fusarium Wilt does not effect every kind of tomato plant and as with Verticillum, it is characterized by the yellowing and wilting of the leaves beginning at the base of the plant and effective initially only one side of the plant. Gleason and Edmunds from Iowa State cite various prevention methods for wilt which, include rotating crop, using soil that is not infected, and keeping the soil well drained.

In order to have healthy tomato crop, one should be cautious and follow preventive measures to ensure that the various tomato diseases do not infect their crop. A gardening book or a local greenhouse should be able to provide the grower with additional information on how to detect and control these diseases. In addition local cooperative extensions would provide also provide sufficient assistance and information.