Tomato Plant Treatment for Disease & Insects

Fungal Wilts

• Two fungal wilt diseases, verticillium wilt and fusarium wilt, attack tomatoes and other common garden plants. Both diseases cause the lower leaves of tomato plants to wilt and yellow. As the disease progress, the entire plant often dies. Contact an agricultural expert to confirm a diagnosis of verticillim or fusarium wilt because the disease's symptoms mimic watering problems, according to the Kemper Center for Home Gardening. Destroy any plants that are infected with a wilt disease. Throw away the plants, but do not compost them. Plant disease-resistant tomato varieties -- look for plant labels with an "F" or "V" on the tag. Avoid planting tomatoes in the same spot for about three years following a wilt infection.

Blights

• Spotted leaves and stems often indicate the presence of one of three common tomato blight diseases. Dark gray to black circular spots developing on lower leaves after the first fruits set indicate septoria blight or septoria leaf spot. Early blight symptoms include target-shaped spots on the leaves and fruit of the tomato plant. Cankers, or sunken spots, often appear on the stalks of infected tomato plants. Late blight causes dark green to black spots to develop on leaf edges, slowly spreading to the leaf's center. Green, water-soaked spots also develop on the fruit and stems. Control blight disease by destroying infected plants. Treat healthy plants with fungicide as symptoms develop elsewhere in the garden. Rotate the location of tomato plants every three to four years.

Bacterial Canker

• Another disease that requires infected plants to be destroyed is bacterial canker. Bacterial canker cause white, scale-like growths to develop on tomato fruits, brown streaks on leaves and wilting plants. Like fungal wilts, the disease may require confirmation by an agricultural expert.

Rots

• Two rot diseases are known to be problems in the tomato garden, including blossom-end rot and root rot. Blossom-end rot causes water-soaked, tan lesions to develop on the blossom end of a tomato fruit. As the diseases progresses, the lesions turn dark and leather-like. Treat blossom-end rot by watering the plants and applying a calcium supplement. Rotting roots often indicate poor soil drainage or the presence of fungi in the soil. Treat rotted roots by improving drainage, avoiding overwatering plants and rotating the crops to new locations every three years.

Pest Problems

• Insects may pose a potential threat to an otherwise healthy tomato crop. Stink bugs, brown or green shield-shaped insects, feed on plants and fruit causing dark pinpricks surrounded by a lighter halo. Keep the tomato garden properly weeded to eliminate the habitat for tomato pests. Yellow leaves accompanied by a sticky, honeydew substance indicates the presences of whiteflies and aphids. Generally, the damage to the plants and fruits is minimal. Treat with an insecticidal soap if the problem does not clear up on its own.