Common Tomatoes pests

The signature pest is the tomato hornworm and the closely related tobacco hornworm, large green caterpillars with a rear horn that strip foliage and leave dark droppings and bare stems. Tomato fruitworm (corn earworm) bores into green and ripening fruit, while flea beetles pepper young leaves with tiny shot holes and Colorado potato beetles chew both tomato and potato foliage. Sap-suckers include aphids and whiteflies that yellow leaves and coat them with sticky honeydew, plus spider mites that stipple and finely web the foliage, plus stink bugs and leaf-footed bugs that cause pale cloudy spots on fruit. Cutworms sever seedlings at the soil line, root-knot nematodes stunt roots, and deer, groundhogs, squirrels, and birds will sample the fruit.

Common diseases

Early blight shows as brown target-ringed spots on lower leaves with yellowing around them, and Septoria leaf spot makes many small circular spots with dark borders and pale centers. Late blight is the most destructive, producing greasy gray-green blotches on leaves and stems and firm brown lesions on fruit during cool wet spells. Soilborne Fusarium and Verticillium wilts cause one-sided yellowing and wilting even when soil is moist, while bacterial spot and speck create small dark greasy lesions on leaves and scabby spots on fruit. Viruses such as tomato mosaic and tomato spotted wilt bring mottled, distorted, or ringspotted foliage, and blossom end rot, though a calcium and watering disorder rather than an infection, leaves a sunken dark patch at the fruit bottom.

Prevention

Rotate tomatoes and their nightshade relatives (peppers, potatoes, eggplant) out of the same bed for three to four years, and choose varieties with resistance codes like V, F, N, and TSWV for problem diseases. Space plants generously and stake or cage them so air moves freely and foliage dries quickly, and keep the lowest leaves pruned off the ground. Water at the base with drip or a soaker in the morning to keep leaves dry, mulch to stop soil from splashing spores onto plants, and avoid handling plants while wet. Clean up fallen leaves and fruit through the season and remove all plant debris at seasons end, since many pathogens overwinter in it.

Organic control

Start with your hands: pick off hornworms, potato beetles, and their egg masses in the morning, and use floating row covers over young transplants to block flea beetles and cutworms, removing the covers once flowers appear so pollinators can reach them. Knock aphids, whiteflies, and mites down with a hard water spray, and treat persistent infestations with insecticidal soap or neem oil applied to the point of good coverage, following the product label. Bt (Bacillus thuringiensis) targets young hornworms and fruitworms without harming beneficial insects, and encouraging lady beetles, lacewings, and parasitic wasps keeps sap-suckers in check; leave hornworms carrying white cocoon-like wasp pupae in place. For fungal and bacterial leaf diseases, copper or sulfur products used preventively during warm humid weather can slow spread, always mixed and applied per the label. Set out pheromone or yellow sticky traps to monitor and reduce moth and whitefly numbers, and fence or net plants against deer and birds.

Scouting & monitoring

Scout at least twice a week, checking leaf undersides for aphids, whitefly clouds, and fine mite webbing, and looking for chewed leaves, droppings, and the telltale bare stems of hornworms. Watch lower leaves as the season warms for the first target spots of early blight or the small dark spots of Septoria, and inspect after every cool, wet, humid stretch for the fast-moving lesions of late blight. Examine developing and ripening fruit for entry holes, cloudy feeding spots, and the sunken end of blossom end rot. Note any sudden one-sided wilting or yellowing, which points to soilborne wilt diseases that call for removing affected plants.

Tips

Catch problems early: a five-minute daily walk with a pail lets you hand-pick pests and snip off the first diseased leaves before either can take over. Keep water off the foliage and give each plant room to breathe, because dry, well-spaced leaves prevent far more disease than any spray can cure.

General home-garden IPM guidance, focused on prevention and least-toxic control. Always read and follow the product label for any pesticide, including organic products. Page updated Aug 4, 2026.