Home Garden Disease Controls
The Pennsylvania State University
Cooperative Extension
Tomato
How important are diseases on tomatoes?
Several diseases affect tomatoes. After tomatoes have been grown in a garden for several successive seasons, leaf spots (early blight and Septoria leaf spot) usually appear and can start to become significant by mid-August. In addition, fruit rots can appear following dry weather (blossom end rot), and when fruit ripen (anthracnose).
What diseases can affect tomatoes?
Listed below are four groups of diseases that most frequently occur on tomatoes. Symptoms are described briefly. Colored pictures of disease symptoms can be seen in the publication Identifying Diseases of Vegetables.
Wilts
Plants wilt and may die. There are several different causes. Special soil fungi (Verticillium and Fusarium) are a common cause of wilt. Walnut trees also are associated with tomato wilting; a toxin from walnut roots causes this problem. These wilts also cause internal woody stem tissue to turn brown.
Control: Avoid garden areas where tomatoes, eggplants, peppers, potatoes, strawberries, and brambles were grown in the past few years. Do not plant near walnut trees. Grow tomato varieties resistant to fungal wilts. As soon as harvest is completed, remove and destroy or discard plants.
Leaf Spots (Early Blight and Late Blight)
Early blight symptoms are dark brown spots with dark concentric rings, usually on oldest leaves. Spotted leaves die prematurely resulting in early defoliation, fruit sunscald, and poor fruit color. Late blight affects fruit and leaves. Irregular, greasy appearing, grayish areas develop on leaves. These areas expand rapidly in wet weather.
Control: Please see fruit rot control below.
Fruit Rots of Tomatoes (Anthracnose, Early Blight, and Late Blight)
Many rots develop on fruit that are touching the ground. Discrete spots also can develop on other fruit. Fruit rots are promoted by contact with the soil and by wet weather.
Control: Choose a sunny garden planting site. Avoid garden areas where tomatoes were grown during the past few years. Insure adequate fertility by following soil test recommendations. Space plants to promote drying-off of leaves and fruit; late stake plants to keep fruit off the ground. Use appropriate labeled fungicides when necessary. Remove plants and the largest roots as soon as possible after harvest is completed.
Blossom-end Rot
This rot appears as a large, dry brown to black, and often depressed, leathery area at the blossom end of fruit.
Control: Insure adequate calcium and other nutrients in the soil by following soil test recommendations. Avoid moisture stress by mulching around plants, watering plants when soil is dry, and by avoiding close cultivation which breaks roots.
Note: Where trade names are used, no discrimination is intended
and no endorsement by the Cooperative Extension Service is implied.
Information provided is intended for consideration by the user, but is not
intended to be a recommendation. Production decisions should be based on
consideration of many types of information (scientific, experiential, economic,
legal, etc.) available to the user.
