Diagnosing Common Tomato Problems in Texas Fall Vegetable Gardens

Planting tomatoes in the worst of summer’s heat seems destined for failure. However, early July is the best time to add new tomato plants for fall harvesting by allowing them time to establish before they blossom and fruit in the cooler weather of September.

Planting Tomatoes for Fall Vegetable Garden in North Texas

Before planting, choose an area to plant tomatoes that has not grown members of the nightshade family for two years including tomatoes, potatoes, eggplant or hot peppers. Clear the area of weeds; add 2 inches of compost and a small amount of sterile manure. Turn the top layer of soil about 1 to 2 inches deep to mix the soil, compost and manure.

Seedlings or transplants work better than seeds to start tomato plants, although you can start seeds indoors in May for transplanting. The varieties available for fall vegetable gardens are more limited than in the spring. However, gardeners can find celebrity and sweet 100’s varieties at most nurseries beginning in early July.

Remove the lower two leaves and place so that the lowest remaining leaves are about 1 inch above the soil. Angle the root ball and stem slightly in the hole so that the buried part of the plant is about 1.5 inches below the surface. This allows the feeder roots to get moisture and nutrition more easily. Water immediately and thoroughly. Mulch the plants 2 inches away from the stem. Continue watering daily until the plants establish. After two weeks, test for moisture at least every other day. If the soil is dry below 1 inch, water.

Tomato Fruit Problems

Brown spots on ripening or green fruit usually indicate bacterial attack. Lower leaves of the plant may wilt and turn brown. If diagnosed early, copper sprays may control the bacteria. However, bacterial problems spread among plants. Therefore, if the diseased plant’s problems are more than superficial, that is more than just a few specks on one or two tomatoes, it is best to remove the diseased plant entirely.

Blossom end rot, a common problem in spring tomatoes, is caused by moisture stress. Characterized by deterioration of the blossom end of the fruit, it manifests as a sunken appearing dark area that is soft to the touch. According to Texas AgriLife, blossom end rot is a physiological disorder caused by calcium deficiency induced by water stress. They recommend careful water management, raised beds to improve drainage and mulch. The absence of calcium in the soil is not the problem. Rather, the plant’s inability to use the calcium because of moisture stress leads to blossom end rot. Most North Texas soils contain sufficient calcium.

Cracking involves the presence of large fissures on the fruit radiating out from the stem connects to the fruit. Early blight, also at the stem scar, manifests as black or brown leathery are of lesions. A gardener will notice early blight first on leaves by the appearance of irregular brown lesions and yellowing tissue. Blossom end rot, cracking, and early blight are less common in fall vegetable gardens than in spring gardens.

Harvest ripe tomatoes in October through early November. Before the first freeze, pick the green tomatoes and ripen them individually in wrapped newspaper. Alternately, process them to make tomato chowchow or mock mince meat.

The Texas A&M AgriLife website offers pictures of tomato plant diseases to help make the correct diagnosis and develop a treatment plan.