Tomatoes are one of the most common and popular plants in the vegetable garden. They are subject to many problems, some caused by insects, others by fungus and a few by weather conditions. Recognizing the symptoms allows gardeners to identify the problem and seek the appropriate treatment.
Curly Top Virus
The beet leafhopper spreads curly top virus, and there is no treatment for this disease. Signs of infection include plants with yellow leaves which quit growing. Leaves toward the top of the plant turn a purple color, predominantly around the veins. Leaves and stems stiffen and fruit ripens early. The leafhopper migrates from southern climates, and hot, dry spring weather encourages the spread of this disease.
Tomato or Tobacco Hornworms
This common caterpillar feeds aggressively and can strip leaves and stems, as well as feeding on unripe fruit. They are green to grayish-green with white or tan V-shaped markings on their bodies. A reddish brown hook protrudes from their rear end. Remove the pests by hand or treat plants with common insecticides.
Psyllids feed on the sap of tomato or potato plants. The result is yellowed leaves with purplish veins. The stems of the plant take on a zigzag appearance. Small like aphids, the yellow or green nymphs are stationary while feeding and leave a granular substance behind that resembles sugar. They can be treated by dusting the plants with sulfur, paying extra attention to the underside of leaves.
This fungus is prevalent during the hotter months of the growing season. Telltale signs are black or brown spots resembling targets, primarily on older leaves. Serious infections can affect stems and fruits as well. Leaves turn yellow and drop. Fruit is then overexposed to the sun and can burn. Remove infected leaves from plant and from the ground. Dusting with sulfur may protect emerging leaves. Avoid watering from above and space plants farther apart to provide better air flow.
Fusarium Wilt and Fusarium Crown Rot
Fusarium oxysporum is the fungus causing fusarium wilt and fusarium crown rot. and is carried through the plant by its water absorption and distribution system. With Fusarium crown rot, older leaves yellow and then turn brown or black before wilting. Cutting the main stem open will reveal a brown discoloration within. A canker will appear near the base of the stem. Fusarium wilt also yellows older leaves, which then wilt. There is no treatment for the disease.
Blossom End Rot
Tan-colored, water-soaked sores appear at the blossom end of the fruit. As they grow, the lesions blacken and become leathery. Fluctuations in heat and cold during the time blossoms are forming along with changes in water supply are believed to cause the problem. These two conditions create a calcium deficit during the formation of the fruit. There is no treatment. It can be avoided by not putting plants out too early and by managing watering practices.