Homegrown tomatoes, far superior to their supermarket counterparts, are not difficult to grow. Tomatoes are, however, subject to a variety of pests and diseases. Fortunately, most problems can be controlled or eliminated if caught and treated early. Troubleshooting tomato plants requires a careful eye; take the time to inspect your plants regularly for signs of weakness or damage so you can take action early to preserve your harvest.
Choose the right location. Tomato plants need at least six hours of sunlight. Lacking sufficient sunlight, plants will become leggy and weak.
Set plants out at the right time and protect from frost. Tomatoes perform best when nighttime temperatures remain above 55 degrees Fahrenheit, and a frost can kill young plants. Consult a USDA zone chart to determine the optimum date for planting date for tomatoes. Symptoms of frost damage include curled leaves with brown, dead edges. Watch the weather carefully during the early weeks of the gardening season and cover young plants with a floating row cover or cloche when temperatures are predicted to drop below 40 degrees Fahrenheit.
Install cages early. Tomato cages or cones support the plants as they grow and keep fruit off the ground, away from pests. Tomato plants can be grown without cages, but the plants will grow horizontally, taking up more space than necessary. In addition, sprawling plants are subject to rot and pest damage. Soft, black spots at the blossom end indicate rot. Slug damage causes damage to the skin of the fruit.
Protect seedlings from cutworms. During the first month of growth, small seedlings are vulnerable to cutworm attack. These 2-inch worms will girdle and kill small seedlings. Wrap a 2- to 3-inch strip of newspaper around the stem of the plant. It will deteriorate as the plant grows larger.
Water regularly but carefully. Tomatoes require deep, regular watering for the best fruit production. Symptoms of inconsistent watering include split, cracked or deformed fruits and rot at the blossom end.
Watch for aphids. Aphids damage rarely kills tomato plants, but these small white insects can damage foliage and weaken the plant. Aphids congregate on the undersides of the leaves and can be treated with insecticidal soap. Spray the plants thoroughly and regularly until signs of infestation are gone. This may require repeated applications over a one- to two-week period.
Prevent fungus and viral infections by planting resistant tomato varieties. Soil borne fungi like fusarium and verticillium cause damage to the stem and leaves. The plant cannot get sufficient nutrients eventually dies. Destroy any contaminated plants and rotate crops every two to three years.