Protecting tomatoes from pests is easier when you spot problems early and make the garden less inviting to insects without harming pollinators. Start by checking plants regularly, identifying the pest before treating it, and using the least disruptive control that works. You will need a few basic supplies, but you do not need to spray on a fixed schedule.
What You’ll Need
- Garden gloves and a small bucket of soapy water
- A hand lens or phone camera for inspecting small insects and leaf damage
- Plant ties, stakes, or cages to keep foliage off the soil
- Lightweight insect-exclusion row cover, if suitable for your climate and plants
- Optional: a hose with a gentle spray setting and a pesticide labeled for tomatoes and the pest you have identified
Step-by-Step
- Check plants at least twice a week. Look over the tops and undersides of leaves, stems, flowers, and developing fruit. Check especially near leaf veins and growing tips, where aphids, whiteflies, and mite colonies often gather. Inspect more often during hot, dry weather or when nearby plants have pest problems. Note whether damage is spreading, and take a photo so you can compare it later.
- Identify the pest before acting. Holes, curling leaves, and yellowing can have causes other than insects, including disease, heat, or watering stress. Look for the pest itself, eggs, shed skins, sticky honeydew, webbing, or fresh droppings. Tomato hornworms are large green caterpillars that may be hard to see; look for stripped leaves and dark droppings on the plant or soil. Ask a local extension service or garden expert if you cannot identify the cause.
- Remove larger pests and damaged material by hand. Pick off hornworms, caterpillars, and beetles and drop them into soapy water, or move beneficial insects elsewhere. Remove leaves heavily covered with pests, but do not strip the plant. For aphids, a firm but gentle stream of water can dislodge colonies; repeat as needed and avoid soaking flowers or leaving foliage wet overnight. Check the plant again after a day or two.
- Keep plants supported, spaced, and tidy. Stake or cage tomatoes so leaves and fruit are not resting on the soil. Follow the spacing recommendations for your variety, allowing air and light to reach the foliage. Remove fallen leaves and overripe or damaged fruit promptly, and clear plant debris at the end of the season. Do not compost diseased or heavily infested material unless your composting process reliably destroys pests and pathogens.
- Use barriers before pests arrive. Cover young plants with insect-exclusion mesh or row cover to block some moths, beetles, and other insects. Secure the edges so pests cannot crawl underneath. Covers can also trap pests already on plants, so inspect and remove insects before covering. Tomatoes need pollination to set fruit; once plants flower, remove covers or open them regularly to allow pollinators access, unless you are hand-pollinating. In hot weather, covers can raise temperatures, so ventilate or remove them if plants overheat.
- Encourage helpful insects and reduce hiding places. Grow a mix of flowering plants nearby to provide food and shelter for beneficial insects such as lady beetles, lacewings, and tiny parasitic wasps. Avoid broad-spectrum insecticides, which can kill these allies as well as pests. Rotate tomato planting locations each year when possible, and remove volunteer tomatoes and related crop debris that may carry pests into the next season.
- Use a pesticide only if needed, and follow its label exactly. Choose a product specifically labeled for tomatoes and the pest involved. Read all directions, including the application rate, protective equipment, re-entry interval, and pre-harvest interval—the time to wait between application and picking. Never exceed the labeled dose or mix products unless the label permits it. Apply only under suitable weather conditions, avoid spraying open flowers and visiting pollinators, and keep children and pets away as directed. Organic products can still harm people, beneficial insects, or plants when misused.
Common Mistakes
- Spraying without identifying the problem: It wastes product and may harm natural predators. Confirm that a pest is present and causing damage first.
- Using broad-spectrum treatments as prevention: Routine spraying can trigger new outbreaks by killing beneficial insects. Monitor plants instead and treat only when necessary.
- Applying insecticidal soap or oil in harsh conditions: Heat, drought stress, or direct sun can increase plant injury. Test a small area, follow the product label, and avoid treating stressed plants unless the label says otherwise.
- Leaving row covers sealed after flowering: Tomatoes may produce fewer fruits if pollinators cannot reach the flowers. Remove or open covers when flowers appear, or hand-pollinate if a barrier must remain.
- Confusing all leaf damage with pests: Disease, nutrient issues, and watering problems can look similar. Check for insects and their signs before choosing a remedy.
Tips
- Inspect in the morning when plants are cool and many pests are easier to find.
- Use a light-colored sheet under a branch and tap it gently to reveal small insects that fall off.
- Keep a short record of pest sightings, treatments, and harvest dates. It helps you see patterns and respect pesticide waiting periods.
- Water at the base of plants when practical. Consistent watering helps tomatoes tolerate damage, though it does not eliminate pests.
- Protect nearby herbs and flowers from pesticide drift, and never assume that a product is safe for pollinators just because it is labeled organic.
Troubleshooting
Damage continues after hand-picking: Reinspect at night or early morning, when some caterpillars and slugs are active. Check neighboring plants and the soil surface, remove fresh egg clusters if you can identify them, and repeat manual removal over several days.
Leaves curl or yellow but you cannot find insects: Check soil moisture, recent temperature swings, and the undersides of leaves with a hand lens. If symptoms spread, look for signs of disease and contact a local plant clinic rather than applying an insecticide at random.
A spray seems ineffective: Confirm the pest matches the product label and that you treated the required leaf surfaces. Some products do not work on eggs or larger larvae. Follow label directions for repeat applications; do not increase the concentration or spray more often than allowed.
Plants look worse after treatment: Stop applying the product and check the label for plant-injury guidance. Water normally, keep the plant out of additional stress where possible, and seek local advice if symptoms are severe. Do not harvest until the label’s pre-harvest interval has passed.
Frequently Asked Questions
What is the most common pest on tomato plants?
Aphids, whiteflies, spider mites, and tomato hornworms are common, but the main pest varies by region and season. Inspect the plant to identify the actual problem before treating it.
Can I use dish soap to kill tomato pests?
Household dish detergents are not formulated as plant pesticides and can burn leaves. If you need a soap treatment, use an insecticidal soap labeled for tomatoes and the target pest, following its directions.
Will companion planting keep pests away?
Some flowering plants can support beneficial insects, but companion planting is not a reliable stand-alone barrier. Combine it with inspection, sanitation, and targeted controls.
Should I remove leaves with holes?
Not necessarily. A few holes do not usually justify removing healthy leaves. Remove badly damaged or pest-infested leaves, and keep enough foliage for the plant to grow and shade its fruit.
Can I eat tomatoes after spraying?
Only after the product’s labeled pre-harvest interval has passed. Wash produce under clean running water before eating, and follow any additional directions on the label.
Do marigolds protect tomatoes from pests?
Marigolds may attract beneficial insects, but they do not reliably repel every tomato pest. Use them as part of a diverse garden, not as a replacement for monitoring and direct pest control.