Tomatoes

Tomato Problems

If no flowers form, plants may not be getting enough sun or water. Too little of either can stop flowering.

If plants are producing abundant flowers but no fruit, it could be due to insufficient light, inadequate watering or irregular watering schedule, extreme temperatures (above 75°F during the night and 90°F during the day), or insufficient pollination by bees.

If flowers form but drop off the plant, this is due to high daytime temperatures (over 90°F). Provide shade during the hottest part of the day by using row covers or shade cloth.

Low humidity can also affect pollination. The ideal is 40 to 70 percent. If humidity is low, mist the plant to help pollen to stick.

Tomato Pests

Tomatoes are susceptible to insect pests. To avoid overpopulation of insect pests, follow these basic tips:

1. Monitor tomato plants daily, checking under leaves, checking fruit, and checking near the soil.
2. To dislodge many pests like Aphids, spray plants with a good jet stream from the hose.
3. Handpick bigger insects like Tomato Hornworms with gloves on, dropping them into a bucket of soapy water.
4. Apply insecticidal soap directly to the insect on the plant. This works for smaller pests, such as aphids and spider mites.
5. Apply horticultural oils or sprays diluted in water. Neem oil sprays block an insect’s air holes.
6. If you choose as a last resort to use insecticides like Sevin, keep in mind that you may be killing beneficial insects as well.

When it comes to tomato diseases and other problems, most of the work is in prevention. Here are some tips to avoid tomato diseases:

1. Plant disease-resistant tomato varieties. Tomato disease-resistant codes are listed on seed or seedling packets (example: F = Fusarium Wilt).
2. Rotate crops at least every 3 years in the same spot. Avoid planting other members of Solanaceous/nightshade family in the same area as well. This includes potato, pepper, and eggplant.
3. Ensure well-draining soil. Always mix in compost or organic matter.
4. Water consistently! Do not overwater or underwater. Uneven watering may cause a condition called blossom end rot.
5. Destroy infected plants. Unfortunately, you often need to remove and discard infected plants, or the disease will overwinter. Do NOT put them in your compost pile.
6. Solarize the soil. If the problem is really bad, you can treat your soil by covering it with plastic during the hottest part of the summer for 6 to 8 weeks; the sun will destroy the bacteria.

Tomato Diseases

• Blossom-End Rot causes the bottom side of the tomato to develop dark, sunken spots due to a calcium imbalance due to uneven watering. See the link for remedies and prevention.
• Early Blight is a fungal disease that causes leaves to drop. In July, the risks of blight increase, due to the combination of high humidity and warm days and nights. It starts with dark, concentric spots (brown to black), about 1/2-inch in diameter, on the lower leaves and stems. If you catch it early and destroy infected leaves, your plant may survive. The best defense for outdoor tomatoes is good ventilation and stripping off the lower leaves as the fruits develop. This also helps the ripening process, as tomatoes have maximum exposure to the sun.
• Late Blight is a fungal disease that causes grey, moldy spots on leaves and fruit, which later turn brown. The disease is spread and supported by persistent damp weather. Unfortunately, once your tomato has late blight, there’s really no solution.
• Mosaic Viruscreates distorted leaves and causes young growth to be narrow and twisted, and the leaves become mottled with yellow. Unfortunately, infected plants should be destroyed (but don’t put them in your compost pile).
• Fusarium Wilt starts with yellowing and wilting on one side of the plant and moves up the plant as the fungus spreads. Unfortunately, once this disease strikes, the plant needs to be destroyed.
• Powdery Mildew is a fungal disease that leaves white spots or a dusting of white on the leaves. It can be managed. See the link to learn more.
• Cracking: When fruit growth is too rapid, the skin will crack. This usually occurs due to uneven watering or uneven moisture from weather conditions, such as (very rainy periods mixed with dry periods). Keep moisture levels constant with consistent watering and mulching.

See more information about Tomato Diseases and Disorders.