Tips to Keep Tomato Plants Healthy

By Mallory Kelley

The tomato is by far the most popular plant in the vegetable garden, but it can also be the most problematic. There are many things to watch for when growing tomatoes to ensure a healthy crop.

Plants are happiest if the leaves never get wet, so eliminate water on the foliage as much as possible with drip irrigation or hand-watering. If using an overhead sprinkler, water early in the morning so the sun will dry the foliage as soon as possible.

Pruning all lower limbs that are touching or near the surface of the soil will also help prevent fungal spores from splashing onto the leaves. Mulch creates a barrier between the plant leaves and the soil to help suppress many of the fungal spores that may splash onto the leaves from the ground. In addition, mulching plants will help the soil retain moisture and keep the plant’s moisture level more consistent. It also helps prevent blossom-end rot and suppress weeds. As the mulch breaks down, it adds organic matter to the soil. Remove yellow- and brown-spotted leaves as soon as they appear, as this indicates a fungal disease. Removing diseased leaves quickly will help stop the spread. If you haven’t already, start a fungicide application to prevent early blight. Nearly every tomato plant in the Southeast is going to get a fungal disease caused by Alternaria solani — but a preventative fungicide can help protect plants. Use products with the active ingredients chlorothalonil, mancozeb or copper.

Scouting daily for insects to catch the pests early is also a must. Then, accurate identification is the key to success.

The Alabama Extension smartphone app Farming Basics can help with identification and control. Familiarize yourself with the most common pests — armyworms, fruitworms, hornworms and stinkbugs.

Bacillus thuringensis (Bt) products are labeled organic. However, Bt products will only control worms in your garden. Apply early when the worms are small and actively feeding on the plants. The bacteria acts as a gut poison to the worm. If the worms are large before spotting them in the garden, it may be too late for sprays to be effective. More lethal products, like those that contain carbaryl, would be needed. Remember: Carbaryl is not selective like Bt, so it will kill a wide range of good and bad insects in a vegetable garden.

Other insects that like tomatoes are the stinkbug and leaf-footed bug. These can be very hard to control, so the best active ingredient in the home garden is bifenthrin. With any of these products, be sure to read the label and the post-harvest interval to learn how many days you must wait after application before picking and eating the fruit.

Weather challenges, garden insects, viruses, fungal problems, bacterial issues and disorders are all part of growing backyard tomatoes. If you have more questions about what may be affecting your tomato plants, call the Master Gardener Helpline at 1-877-ALAGROW (252-4769).