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Tomato Killers and How To Stop Them

By this time of year, your tomatoes should be growing and beginning to flower. You don’t want to worry about pests and diseases. Learn the basics on some common tomato killers and how to stop them.

Tomatoes

Tomato Killer One:  Pests

Several types of pests can infest your tomatoes. Keep an eye out for all of these.

Aphids

Aphids

Aphids can exist on your tomatoes without causing much damage; however, if your leaves are curling, yellowing, or coated in aphids, it’s time to take action.

They are small, soft-bodied green or yellow insects, but they may sometimes also be black, red, pink, or brown. They will coat the underside of your leaves or the shoots of the plant, secreting a sticky, sugary substance called honeydew, which then contributes to and encourages sooty mold.

To deter aphids, you can use reflective mulch and seek tolerant varieties of tomatoes to plant.

To get rid of them, you can prune the leaves where the infestation occurs, crush them by hand, or spray them with a powerful jet of water.

Cutworms

Cutworm

Cutworms chew through the stems of your plants at ground level. These brown or green caterpillars form into a C shape when they are disturbed. Their larvae work at night to chew through the stems of your tomatoes, and one morning, your previously healthy plant’s stem will be cut off at ground level.

To prevent cutworms, you can weed all beds thoroughly at least 2 weeks before planting, especially if last year’s crop was another host plant, like beans, carrots, peppers, or alfalfa.

To get rid of cutworms, you can protect your plants with foil or paper collars around the plants. You’ll insert the collars into the soil at least 2 inches deep, and they’ll need to extend about 5 inches above the soil. You can also try removing the larvae by hand after dark or scattering diatomaceous earth around each plant to create a barrier the cutworms won’t cross.

Hornworms

Hornworm

Tomato hornworms are large (1-5″) green caterpillars with either 7 diagonal stripes or 8 v-shaped markings on their sides and a horn on the tail end. They eat stems, leaves, and fruit and have been known to totally destroy young tomato plants.

To prevent hornworms, cultivate populations of wasps and praying mantises, which are natural predators. Certain types of wasps will parasitize the hornworm’s body for their eggs, which should be encouraged.

To get rid of hornworms, hand-pick them at their most active time of day, in the early evening. Mulch garden beds thickly between growing seasons to kill larvae.

Stink Bugs

Stink Bug

Shield-shaped, brown or green stinkbugs carry pathogens that can cause fruit to rot. They lay clusters of drum-shaped eggs on plant leaves and winter under the leaves. White or green patches mark where they have fed on your tomatoes.

You can prevent stinkbugs by weeding thoroughly around garden beds at least 2 weeks before planting.

You can get rid of stinkbugs by hand-picking them from leaves or snipping them with garden shears. Use a bucket of soapy water under leaves, since they will drop from the plant if they are disturbed. Do not use insecticides.

Snails and Slugs

Snail  Slug

Snails and Slugs will feed on plants that are near the ground. Avoid giving them easy access to fruit, as they can eat large chunks if given the opportunity.

To prevent snails and slugs from eating your tomatoes, make sure you are keeping the leaves and fruits off the ground by using stakes and cages.

Tomato Killer Two:  Diseases

Diseased Tomato

Tomatoes are impacted by a wide variety of diseases. Learn more about the more common diseases below.

Bacterial Wilt

Bacterial wilt can exist in your soil for extended periods of time and seriously impact your tomato plants. It thrives in high temperature, high moisture environments, and is primarily characterized by the rapid wilting of your plant, even though the leaves stay green.

To prevent bacterial wilt, choose certified disease free plants and rotate crops frequently. Make sure plants are not over-watered.

To stop bacterial wilt, remove and destroy all infected plant material.

Blossom End Rot

Blossom end rot will begin as tan, water-soaked spots on the blossom end of the fruit. They will soon enlarge and become black. This is caused by a calcium deficiency in the soil and the fruit. Calcium deficiency can be caused by irregular watering or from using fertilizers with magnesium, ammonium nitrate, or potassium.

To prevent blossom end rot, keep your soil at a pH of 6.5 and water regularly. Mulch around your plants to help your soil stay cooler and keep a steady stream of water to your soil.  Mulch also helps prevent weeds, which reduces the need for weeding or cultivating that can damage tomato plant roots. Also, look for tomato varieties that are resistant to blossom end rot and avoid over-fertilizing.

To stop blossom end rot, remove symptomatic fruit from the plants.

Early Blight

Early blight first appears as brown lesions on any of the older foliage on your plants. Lesions will expand on the leaves, with a bull’s-eye pattern emerging in the center of the spots. Stem lesions will follow, which look similar to the pattern on the leaves. Infected fruit also develops concentric rings and drops from the plant.

To prevent early blight, space plants far enough apart that they will not touch and spread the disease, rotate crops, and purchase resistant tomato varieties.

To stop early blight, remove infected branches and leaves and use a fungicide developed for blight at the first sign of the disease.

Late Blight

Late blight thrives during cool, wet weather and affects all parts of your tomato plants. Dark, wet spots will appear on your leaves, which will expand quickly, with white mold appearing at the edges of the spots. Within 14 days, the leaves on infected plants may be completely shriveled and brown. Shiny, dark olive-colored spots will appear on the fruit and can cover large portions of the tomato.

Choosing resistant tomato varieties, spacing your plants far apart, and avoiding overhead watering of your plants can help prevent late blight.

Pull and destroy all diseased plants or use the appropriate fungicide to get rid of late blight.

Growth Cracks

Cracked Tomato

Tomatoes crack when they ripen under conditions that encourage rapid growth, like sudden periods of rain after a drought. The fruit grows too quickly for the skin to keep up. If cracks continue to grow, they can become quite large and invite fruit rot.

To prevent growth cracks, maintain consistent moisture in the soil by mulching or watering regularly. Look for crack-resistant varieties.

Green Tomatoes on the vine

This is a basic list of tomato killers to get you started. Click here and here for more exhaustive lists of pests and diseases that can affect your tomato plants.

Don’t forget to comment with your tips on getting rid of tomato pests and diseases!

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