The tomato bush or vine is the quintessential plant for your backyard garden. They are relatively low-maintenance and produce large amounts of plump, red fruit that's ideal for both raw and cooked use. Even a hardy plant like a tomato can sometimes experience stunted growth, insect invasions and other health problems that affect your harvest. Troubleshoot your tomato plant to resolve these issues and keep your garden healthy, lush and productive.
Dry the tomato plants' foliage. Plants that are planted too close together--space the plants apart by 24 inches--or whose foliage is consistently wet are susceptible to many tomato plant diseases.
Increase sunlight if you notice poor fruit production or yellowing foliage. Growing fruit requires a lot of energy and tomato plants need a minimum of seven hours of direct sunlight per day. Prune back surrounding trees or plants to increase sunlight on your tomato garden plot, or move the plot to a new location.
Supply enough water if you find your plants wilting or if the developing fruit stay small. Tomato fruits are 95 percent water and need lots of moisture for proper growth. Give your tomato plants approximately 2 qts. of water daily until the plant starts growing fruit, after which you should increase the daily water application to 3 to 4 qts.
Feed the plants if you notice stunted growth or poor fruit production. Use a standard vegetable fertilizer with a low ratio of nitrogen--ideal ratios include 5-10-10 and 8-16-16--and apply according to the fertilizer's label, since potency varies by product. High amounts of nitrogen will encourage undesirable foliage production.
Treat any pests on your tomato plants, such as aphids, beetles and white flies, if you discover them on your plants. These stress or weaken the plant and sometimes damage the tomato fruit. Use a general insecticidal soap or, for heavy infestations, a species-specific insecticide. If you are unsure of the type of pest that's afflicting your tomatoes, capture a sample and bring it to a nursery or garden store for suggestions from the staff.