Garden Pests & Diseases

Microscopic soil roundworms that swell roots into knotty galls, starving the plant. Plants wilt in the heat of the day, yellow and stay stunted no matter how you feed and water. Worst in Florida's sandy soil, especially on tomato, okra, beans, cucurbits and many others.

Manage it: plant nematode-resistant varieties (look for the "N" on tomato labels); rotate crops; flood the soil with organic matter and compost; solarize beds with clear plastic for 6 weeks in summer; and grow a knockdown cover crop (French marigold 'Tangerine' / 'Single Gold', or sunn hemp) in the off-season. There is no quick organic cure once a crop is infested, so build the defense between crops.

Tiny white moth-like insects that fly up in a cloud when you brush the plant. They suck sap, coat leaves in sticky honeydew (which grows black sooty mold), and spread viruses like Tomato Yellow Leaf Curl. Worst on tomato, squash, beans and many ornamentals.

Manage it: blast them off with water, use yellow sticky traps to monitor, encourage lady beetles and lacewings, and spray insecticidal soap or horticultural oil on the leaf undersides where they hide. Remove and bag virus-infected plants promptly. Reflective silver mulch deters them early in the crop.

Small green, black or gray insects that cluster on new growth and leaf undersides, causing curling, distortion and honeydew. They build up fast in the cool season on lettuce, brassicas and beans.

Manage it: a hard spray of water knocks them off; insecticidal soap or neem handles heavier infestations. Lady beetles, lacewings and hoverflies are voracious predators, so avoid broad-spectrum sprays that kill them too. Nasturtiums make a useful trap crop.

Includes the big green tomato/tobacco hornworm (with a tail horn), plus armyworms, cabbage loopers and webworms on brassicas, and corn earworm in corn tips. They chew large holes and can strip a plant overnight.

Manage it: hand-pick (hornworms are big and easy once you spot the frass below them), and use Bacillus thuringiensis (Bt), a caterpillar-specific organic spray that spares bees and beneficials. Floating row cover keeps moths off young brassicas. Leave hornworms covered in white wasp cocoons in place, as those are beneficial parasitic wasps doing your work.

The vine borer is a fat white grub that tunnels inside squash and pumpkin stems, causing sudden wilt and sawdust-like frass at the base. The pickleworm bores into squash and cucumber fruit. Both are relentless in the Florida warm season.

Manage it: grow borer-resistant Seminole pumpkin and butternut (solid stems); plant early or in fall to dodge peak moth flights; cover young plants with row cover until flowering; mound soil over the vines so they root along the stem; and inject Bt or slit and remove the grub if you catch wilt early. Succession-sow so you always have a younger plant coming.

Shield-shaped stink bugs and the larger leaf-footed bugs pierce fruit (tomatoes, peppers, beans, peaches), leaving hard, discolored, dimpled spots. Their clusters of bronze eggs and spiky young nymphs are common on tomatoes in spring.

Manage it: hand-pick adults and crush egg masses in the morning when they are sluggish; remove weedy harborage nearby; and target young nymph clusters with insecticidal soap (adults are tough to spray-kill). Row cover protects fruiting crops early.

Spider mites are nearly invisible specks that cause fine yellow stippling and webbing, exploding in hot dry spells. Thrips rasp leaves and flowers to a silvery streak and spread tomato spotted wilt virus.

Manage it: mites hate humidity and water, so hose down leaf undersides; use insecticidal soap or horticultural oil and predatory mites. For thrips, use blue sticky traps, remove spotted-wilt plants, and protect with reflective mulch. Avoid over-fertilizing with nitrogen, which feeds both.

Ragged holes and silvery slime trails on seedlings and leafy greens, worst in the wet season and shady, mulched beds.

Manage it: hand-pick at night or after rain, set beer traps, hand-pick under boards used as lures, and scatter iron-phosphate slug bait, which is pet- and wildlife-safe. Keep mulch pulled back from tender seedlings.

Florida humidity drives leaf spots, early blight (target-ring spots on tomato), downy and powdery mildew on cucurbits, and anthracnose on fruit. Look for spreading spots, fuzzy growth or rotting fruit.

Manage it: space plants for airflow, water at the roots in the morning (never wet foliage at night), mulch to stop soil splash, rotate crops, and choose resistant varieties. Copper or biofungicides (Bacillus subtilis) help as protectants; remove and bag badly affected leaves. Don't compost diseased material.

Bacterial leaf spot (tomato, pepper), bacterial wilt, and the soil fungi Fusarium and Verticillium wilt cause sudden one-sided wilting, yellowing and collapse with no recovery. Common in warm Florida soils.

Manage it: there is no spray cure, so lean on resistant varieties (the V/F codes on tomatoes), long crop rotations, clean tools and seed, and removing infected plants immediately. Grafted tomatoes on resistant rootstock are worth it in problem beds.

A sunken black patch on the bottom of tomatoes, peppers and squash. It is not a disease or pest; it is a calcium issue driven by uneven watering in Florida's fast-draining sand.

Fix it: water deeply and consistently, mulch to steady soil moisture, and avoid heavy nitrogen feeding. A soil test will confirm whether calcium or just water is the issue.

Spread by the Asian citrus psyllid, citrus greening causes blotchy mottled leaves, lopsided bitter fruit, and slow decline with no cure. It has devastated Florida citrus.

Manage it: buy only certified, disease-free trees from a registered nursery; control psyllids; feed and water well to keep trees vigorous; and remove confirmed-infected trees so they don't seed the neighborhood. Report suspected cases to your county Extension office.