How to Identify the Problem With a Tomato Plant


Tomatoes are a popular warm-season plant throughout the United States. The plant is a tropical and semi-tropical plant that is typically grown as an annual in cooler climates. Although the plant has a sprawling habit, most gardeners train it to grow vertically in cages, trellises and wire baskets. Though the plant is simple to grow, it can suffer from a number of diseases, insects or fungus problems. Identifying a problem with Tomatoes is simple.

Step 1

Investigate the history of the soil. Tomato plants that are planted in the same soil yearly, or are planted in soil that once held potatoes or eggplant may develop wilt or blight diseases that were introduced to the soil in previous years. Wilt diseases cause the plant to droop and turn yellow. Blight will cause blotchy leaves with dark, irregular shaped spots. If the blight is severe, the leaves can drop off the plant, causing sun scald on the fruit.

Step 2

Examine your garden surrounding your tomato plants. A tomato plant can contract pests, diseases and diseases from surrounding garden plants. Some garden plants can cause bad reactions to tomatoes. For example, tomatoes planted near walnut trees will be poisoned by the toxins released by the roots and then develop walnut wilt. Tomatoes planted near peppers will not thrive, and if a tomato is planted near corn, both plants will become infested with worms. Additionally, tomatoes that are stressed from low light, too much light or compacted soil may develop a grayish exterior and a brownish interior.

Step 3

Record the weather conditions as your tomatoes are growing. Tomatoes that suffer from catface, which is a scarring of the fruit, are the result of adverse weather conditions that occur during the fruit's development.

Step 4

Test the soil around tomatoes using a home testing kit. Testing kits are available at any garden center. Tomatoes that develop soft, brown spots on the blossom end are the result of a lack of calcium due to too much watering or a pH unsuitable for the plants. Tomato plants that have a yellowing pattern with green veins are due to a lack of nutrients in the soil.

Step 5

Examine your plants for signs of problems due to disease, molds, bacteria or pests. Plants that appear stunted with knotty roots have a buildup of nematodes in the soil. Plants that have thin, blade-like leaves have an aphid problem. Blight creates irregularly spotted leaves and fruit. Wilt will cause leaves to wilt and will turn the plant's vascular system brown. Blight will cause the leaves to wilt and will create a sunken appearance in the stems of tomatoes. Cankers will cause leaves to wilt and will create a yellowish discoloration in the plant's vascular system.

Step 6

Look over tomato fruit for further signs of tomato problems. Leathery discoloration on tomatoes that touch the ground is a sign of buckeye rot, while late blight can cause black, greasy discoloration of the fruit around the stem area. Bacterial spot can create spots on your tomatoes that later take on a scabby, sunken appearance.

Step 7

Record your observations about your tomatoes with a camera. Take cuttings and place them in plastic bags. Take your photos and cuttings to your county agricultural extension agency. Agents at these offices can help make a positive identification of your disease issues and make objective recommendations on how to fix the issue. This service is free to the public.

Things You'll Need

  • Knife
  • Soil-testing kit
  • Cutting shears
  • Camera
  • Plastic bag


  • Alabama Cooperative Extension Service: Tomato Disease Identification
  • Alabama Cooperative Extension Service: Wilt Disease Identification
  • Alabama Cooperative Extension Service: Tomato Insect Management Guide for Alabama

Who Can Help

  • Mississippi State University: Companion Planting Improves Gardens
  • Texas A&M University: Tomato Problem Solver
Keywords: tomato plants, troubleshooting tomatoes, diseases of tomatoes

About this Author

Tracy S. Morris has been a freelance writer since 2000. She has published two novels and numerous online articles. Her work has appeared in national magazines and newspapers, including "Ferrets," "CatFancy," "Lexington Herald Leader" and "The Tulsa World."