Top 10 Tomato Pests and Problems

A green tomato hornworm hangs from a stem next to a green tomato.
My Garden Life
December 29, 2023
Table of Contents

By Kristen Bailey

According to the National Gardening Association, 3 million Americans plant a vegetable garden each year, and 90 percent of vegetable gardeners plant tomatoes. It seems like some years the tomato crop is beautiful and plentiful, and other years, they’re fraught with problems. Don’t worry. There are plenty of things you can do to keep your tomato crop healthy in any year by watching for these 10 common tomato pests and problems and taking action to solve them.

1. Cracking Fruit

When cracks appear on your ripe tomatoes, it’s probably due to hot, rainy weather after a spell of dry conditions. When it’s not raining, water your tomatoes consistently during the growing season so they don’t get too thirsty and soak up all the rainwater during a downpour.

Close up of tomato on a plant with cracks in the skin of the fruit.

2. Tomato Hornworms

    Hornworms (Manduca quinquemaculata) are one of the most common tomato pests that can kill a mature tomato plant in a single night. These large green worms are about 2-3 inches (5-8 cm) long and have little horns on their heads. They’re hard to spot, since they’re camouflaged to look just like the plant’s stem.

      To prevent hornworms, we recommend you plant marigolds around your tomatoes because their strong scent helps repel hornworms. If your plan is to treat your plants with repellents or insecticides to manage tomato hornworms it’s also helpful to understand the lifecycle of the tomato hornworm. This will help with the best timing for applications and inform you on when to start watching for caterpillar activity.

      Close up of one of the most destructive tomato pests - a tomato hornworm on a tomato plant.

      3. Cat-facing

      If your tomatoes are oddly deformed with ripples, bumps and lumps, they were probably pollinated in temperatures that were too cool. When possible, plant your tomatoes a little later in the season, when the nighttime temperatures are between 55° and 75° F (13-24° C).

      Close up of a large red tomato with a distorted skin condition called catfacing.

      4. Blossom End Rot

      Blossom end rot causes black spots on the bottoms of the tomatoes as they ripen. This is caused by a lack of calcium. Your neighborhood Walmart Garden Center sells soil test kits and additives, such as lime or gypsum, to add to the soil.

      Hand holding a young green tomato with a black rotted area known as blossom end rot.

      5. Blossom Drop

      If your tomato blossoms fall off the plant before tomatoes can develop, it’s likely due to cool temperatures. Tomatoes need the temperature to be between 55° and 75° F (13-24° C) at night to develop properly.

      Close up of yellow tomato blossoms on a tomato plant.

      6. Sun Scald

      Yellow patches that form on the tomato skins eventually turn thin and white and affect the taste of your tomatoes. This is sun scald, and you can prevent it by using tomato cages or other support systems to surround the plants and prop up the branches, which will provide shade for the fruit.

      A cluster of tomatoes all suffering from burned discolored skin caused by sun burn or sun scorch.

      7. Low Yield

      If your plant isn’t producing many tomatoes, and the ones that do grow are small and tasteless, you may have too much nitrogen in the soil, or your plants may be too close together, preventing optimum airflow. Test your soil with a kit from your neighborhood garden center, and follow the recommendations given for adding nitrogen. Plant your tomatoes at least 2 feet (.6m) apart so the wind can pollinate the flowers.

      An empty wicker basket on burlap fabric on a wooden table.

      8. Leafroll

      If your mature tomato plant’s leaves start curling, the culprit is probably high temperatures, wet soil or too much pruning. Rest assured leafroll won’t affect the development of your tomatoes, but be careful not to over-prune and make sure your soil has optimum drainage.

      A close up of a tomato plant with all the leaves curled towards the center.

      9. Bacterial Canker

      Bacterial canker (Clavibacter michiganensis) often starts as yellow dots on ripening tomatoes. If you look closely, you’ll see a dark rim around each spot. This problem occurs naturally, and to treat it, you’ll need to remove the infected plant right away so it doesn’t spread to other plants. Throw away the infected plant and don’t add it to your compost. To prevent bacterial canker, rotate your crops each year.

      Close up of raised spotting on a tomato affected by tomato canker disease.

      10. Early Blight

      Early blight (Alternaria solani) is caused by a fungus that lives in the soil over the winter and appears on the leaves as brown spots with rings around them. Early blight can be treated with a garden fungicide that you can get at your neighborhood Walmart. Rotating your plants each year will help prevent early blight.

      Close up of tomato foliage infected with Alternaria solani - tomato early blight.

        Healthy Tomato Plants Lead to a Hefty Harvest

        Growing tomatoes brings luscious, tasty treats to your table, but they can be a little cantankerous. By staying calm, inspecting your plants regularly for tomato pests and addressing problems right away, you’ll likely come away with more tomatoes than you know what to do with. We’ve got great ideas for ways to use your tomatoes in our article, Use Your Summer Harvest: Fresh Tomatoes 5 Ways.

        A fresh tomato harvest in an open wooden crate.


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