What Is Eating My Tomato Plant Stems

If you’ve found holes, gouges, or entire sections missing from your tomato plants, you’re probably asking, ‘what is eating my tomato plant stems?’ It’s a frustrating sight that can threaten your entire harvest. This guide will help you identify the hidden culprits and give you clear, effective strategies to stop them.

Before you can fix the problem, you need to know exactly what you’re dealing with. The type of damage gives you the first big clue. Let’s look at the common suspects and the specific evidence they leave behind.

Common Culprits and Their Telltale Signs

Different pests cause different kinds of damage. Here’s how to play garden detective.

1. Tomato Hornworms

These are public enemy number one for tomato stems. They are large, green caterpillars that can grow up to 4 inches long.

Damage: They chew large, irregular chunks out of stems, often severing entire branches. They also eat leaves and fruit.
Evidence: Look for dark green droppings on leaves below the damage. The caterpillars themselves are perfectly camouflaged, so you have to look closely.

2. Cutworms

These pests are most active at night and target young, tender transplants.

Damage: They chew through stems at soil level, completely cutting the seedling off. You’ll find a healthy-looking plant lying on its side in the morning.
Evidence: The severed stem. Look for the culprit, a gray or brown curled-up caterpillar, in the soil near the base of the plant.

3. Rodents (Mice, Voles, Rats)

Often overlooked, small rodents can cause significant stem damage, especially in early season.

Damage: Clean, angled cuts on stems, similar to a knife. They may strip bark or gnaw stems partway through. They sometimes take the cut piece away.
Evidence: Small burrow holes near the garden, gnaw marks, and possibly footprints in soft soil.

4. Stem-Boring Insects (Like the Tomato Fruitworm)

Some insects don’t just eat the outside; they bore inside the stem.

Damage: Small holes in stems, often near leaf joints. The stem may wilt suddenly because the inside has been hollowed out.
Evidence: Sawdust-like frass (insect waste) around the entry hole. If you slit the stem open carefully, you might find a small, tunneling larva.

5. Slugs and Snails

These are more common on leaves, but they will climb and feed on soft, young stems.

Damage: Irregular, ragged chewed areas on stems. They leave a slimy, shiny trail of mucus behind them.
Evidence: The silvery slime trail is the dead giveaway. Look for them hiding under mulch, boards, or dense foliage during the day.

Step-by-Step: Diagnosing the Damage

Follow these steps to zero in on the pest.

Examine the Time of Day: Damage appearing overnight points to nocturnal feeders like cutworms, slugs, or rodents.
Inspect the Damage Pattern: Is it a clean cut? A ragged chew? A bore hole? Match it to the descriptions above.
Look for Physical Evidence: Check for droppings, frass, slime trails, or the pests themselves. Look under leaves and in the soil.
Check the Plant’s Age: Cutworms attack seedlings. Hornworms attack established plants. Rodents can attack both.

Effective Control Methods for Each Pest

Once you know the culprit, you can choose the right defense. Always start with the least toxic option.

Controlling Tomato Hornworms

Handpicking: The most effective method. Check your plants daily, especially near the top. Drop them into soapy water.
Bacillus thuringiensis (Bt): This natural, soil-borne bacteria is very effective against caterpillars when sprayed on foliage. It’s safe for people and beneficial insects.
Encourage Beneficials: Braconid wasps are a natural predator. If you see a hornworm with white rice-like cocoons on its back, leave it! Those are wasp larvae that will kill the hornworm and create more wasps.

Stopping Cutworms

Collars: Place a physical barrier around new transplants. Use toilet paper tubes, paper cups with the bottom cut out, or aluminum foil. Push it an inch into the soil.
Diatomaceous Earth: Sprinkle a ring of this fine powder around the stem base. It scratches the cutworm’s body, causing it to dehydrate. Reapply after rain.
Till the Soil: In fall or early spring, tilling exposes cutworm larvae to birds and cold weather, reducing their numbers.

Deterring Rodents

Remove Habitat: Clear away tall grass, weeds, and debris piles near the garden where they hide and nest.
Use Hardware Cloth: Create a cylinder of 1/4-inch mesh hardware cloth around the base of plants, buried a few inches deep.
Traps: Use humane snap traps baited with peanut butter placed near burrows or runways. Check them regularly.

Managing Stem Borers and Slugs

For borers, you may need to carefully slit the stem with a razor to remove the larva, then mound soil over the wound to encourage new roots. For slugs and snails:

Beer Traps: Sink a shallow container (like a yogurt cup) into the soil so the rim is at ground level. Fill it halfway with cheap beer. Slugs are attracted and drown.
Copper Tape: Apply adhesive copper tape around pots or raised beds. It gives slugs a slight electric shock, deterring them.
Iron Phosphate Baits: These are organic slug baits that are safe for pets and wildlife when used as directed. Scatter them around affected plants.

Prevention is Your Best Strategy

A healthy garden is more resistant to pests. Here’s how to build a strong defense.

Garden Hygiene and Maintenance

Clean Up Debris: Remove old plants, fallen fruit, and weeds at the end of the season to eliminate overwintering sites for pests.
Rotate Crops: Avoid planting tomatoes in the same spot year after year. This breaks the life cycle of soil-borne pests and diseases.
Till in Fall: Exposing the soil disrupts insects pupating in the ground.

Encouraging Natural Predators

Your best pest control is already out there. Attract these helpers:

Birds: Put up a bird feeder or bath. Birds eat many caterpillars and insects.
Beneficial Insects: Plant flowers like marigolds, cosmos, dill, and yarrow to attract ladybugs, lacewings, and parasitic wasps.
Toads and Frogs: Provide a damp, shady spot with an overturned clay pot for them to hide in. They eat slugs and insects.

Physical Barriers from the Start

Don’t wait for damage to appear. Use these at planting time:

Install stem collars on all transplants.
Consider using floating row covers over young plants to exclude flying insects (remove when plants flower for pollination).
Use mulch, but keep it a few inches away from the main stem to avoid creating a hiding place for slugs and rodents.

When to Use Insecticides (A Last Resort)

If an infestation is severe, you might consider an insecticide. Always choose the most targeted option.

Identify Precisely: Never spray without knowing exactly what you’re trying to kill.
Choose Organic First: Options like insecticidal soap (for soft-bodied insects), neem oil, or Spinosad are effective against many pests and have less environmental impact.
Follow the Label: This is the law. It tells you the right dose, timing, and safety precautions. Never apply more than it says.
Spot Treat: Only spray the affected plants, not the whole garden. Spray in the early morning or late evening to avoid harming pollinators.

FAQ: Quick Answers to Common Questions

What animal is eating my tomato stems at night?
It’s likely cutworms, slugs, or rodents like voles or rats. Look for the specific damage signs and evidence like slime trails or burrows to confirm.

How do I keep bugs from eating my tomato plants?
Focus on prevention: use collars for seedlings, encourage birds and beneficial insects, keep the garden clean, and inspect plants daily so you can handpick pests early.

What is making holes in my tomato stems?
Small, neat holes are often from stem-boring insects. Larger, ragged holes are from chewing pests like hornworms or slugs. Look for frass or the pest itself near the hole.

Can a tomato plant recover from stem damage?
Yes, many can. If the stem is partially cut, you can often brace it with a splint (like a popsicle stick) and wrap it gently with plant tape. Keep the plant well-watered. If it’s completely severed, it likely won’t recover.

What can I put on my tomato plants to keep animals away?
Physical barriers are best: hardware cloth cages, stem collars, or fencing. Some gardeners have success with homemade sprays using garlic or chili powder, but these need frequent reapplication after rain.

Figuring out what is eating your tomato plant stems is the first and most important step. With careful observation, you can match the damage to the pest. Remember, a proactive garden with good habits and encouraged predators is the most sustainable solution. Start with gentle methods like handpicking and barriers, and you’ll often find you can protect your tomatoes without resorting to harsh chemicals. Your plants will thank you with a healthy, bountiful harvest.