Corn, Sweet

Rapid foliar blight reduces plant vigor and yield; severe infections can kill leaves while stems and fruit often remain initially intact.

Favored By

Cool to moderate temperatures, prolonged leaf wetness, high humidity, cloudy weather, dense foliage, and windborne spores.

What It Looks Like

Angular yellow or pale-green spots on upper leaf surfaces with gray, purple, or dark downy growth beneath, most visible on humid mornings.

Prevention

Plant resistant cultivars where available; improve airflow; use drip irrigation; avoid overhead watering late in the day; remove volunteer hosts.

Management

Remove infected leaves or plants when practical; monitor regional forecasts for cucurbit downy mildew; use a crop-labeled preventive fungicide when local risk is high.

Seeds rot before emergence or young seedlings collapse, producing thin stands and sudden losses in flats or garden rows.

Favored By

Cold or waterlogged soil, contaminated mix or containers, poor drainage, deep sowing, dense seedlings, low light, and overwatering.

What It Looks Like

Pre-emergence seeds become soft and brown; emerged seedlings develop a water-soaked or pinched stem at the soil line and topple.

Prevention

Use sterile seed-starting mix and clean containers; sow at the proper depth; provide warmth, drainage, light, and airflow; avoid crowding and overwatering.

Management

Discard affected seedlings and nearby mix; reduce watering; improve light and airflow. Fungicides have limited value after collapse and must be specifically labeled.

Leaf, stem, and especially fruit infections produce sunken rots, reduce marketable harvest, and continue after picking.

Favored By

Warm wet weather, splashing rain, overhead irrigation, infected seed or residue, dense canopies, and overripe fruit.

What It Looks Like

Round sunken dark lesions on ripe fruit, sometimes with concentric rings of black dots or salmon-pink spore masses; leaves and stems may spot or canker.

Prevention

Use disease-free seed and resistant cultivars; rotate; mulch; stake plants; irrigate at soil level; harvest promptly; remove mummified fruit and debris.

Management

Pick and discard infected fruit; avoid handling wet plants; cool harvested produce promptly; apply crop-labeled fungicides preventively when local guidance recommends.

The pathogen girdles stems at the soil line and rots crowns and roots, causing sudden wilt and plant collapse across a wide host range.

Favored By

Hot, humid weather, moist soil, dense mulch or debris against stems, poor airflow, and repeated susceptible crops.

What It Looks Like

White fanlike fungal growth at the stem base and nearby soil, followed by numerous mustard-seed-like tan to brown sclerotia.

Prevention

Rotate with nonhosts such as corn or other grasses; improve drainage; keep mulch away from crowns; remove debris; avoid moving contaminated soil.

Management

Remove plants plus surrounding soil before sclerotia spread; deep burial may help in tilled areas; soil solarization can reduce survival in hot regions.

For Corn, Sweet: Reviewed Research Library baseline; local occurrence and treatment timing vary.

Systemic viruses stunt plants, distort leaves and fruit, reduce yield, and persist for the plant's life.

Favored By

Aphids or other vectors, infected transplants or seed for some viruses, nearby weeds, continuous host plants, and mechanical sap transmission.

What It Looks Like

Light- and dark-green mosaic, yellow mottling, rings, shoestring or curled leaves, stunting, and bumpy or color-broken fruit; symptoms vary by virus and crop.

Prevention

Use virus-free seed and transplants; plant resistant cultivars; control weeds; use reflective mulch where practical; sanitize hands and tools.

Management

Remove symptomatic plants promptly; manage vectors early but recognize insecticides may not stop rapidly transmitted viruses. No treatment cures an infected plant.

Galls replace kernels or form on leaves, stalks, and tassels; severe infections reduce ear quality and yield.

Favored By

Warm dry periods followed by rain, hail or cultivation wounds, excess nitrogen, young rapidly growing tissue, and susceptible sweet corn.

What It Looks Like

Silvery white swollen galls enlarge and become gray, then rupture to release masses of black powdery spores.

Prevention

Plant resistant hybrids; maintain balanced fertility; avoid injuring plants; rotate and remove crop debris where smut is repeatedly severe.

Management

Remove galls before they rupture and discard them; no effective curative treatment exists, and home-garden fungicide applications are not recommended.

Sap-feeding colonies distort tender growth, cause yellowing and sticky honeydew, and may transmit plant viruses.

Favored By

Soft new growth, excess nitrogen, sheltered plants, and warm moderate weather.

What It Looks Like

Tiny (about 1/16–1/8 in), soft, pear-shaped insects; green, black, yellow, gray, or pink; two tailpipe-like cornicles.

Prevention

Avoid excess nitrogen; inspect leaf undersides; conserve lady beetles, lacewings, hoverflies, and parasitoid wasps; control ants that protect aphids.

Management

Knock off with water; prune badly infested tips; use insecticidal soap or horticultural oil with thorough contact coverage. Repeat only as label directs.

Rasping-sucking feeding scars leaves, buds, flowers, and fruit; some species transmit viruses.

Favored By

Hot, dry weather; flowers and tender growth; weeds and plant debris; stressed plants.

What It Looks Like

Very slender, usually 1/25–1/8 in, yellow, tan, brown, or black; adults have narrow fringed wings.

Prevention

Start with clean plants; remove weeds and spent blossoms; keep plants evenly watered; conserve minute pirate bugs and other predators.

Management

Dislodge with water; remove heavily damaged tissue; use insecticidal soap, horticultural oil, or spinosad where labeled, timed to susceptible stages.

Mites remove cell contents, causing pale stippling, bronzing, leaf drop, and fine webbing during heavy infestations.

Favored By

Hot, dry, dusty conditions; drought-stressed plants; excess nitrogen; loss of predatory mites from broad-spectrum sprays.

What It Looks Like

Minute, eight-legged mites, yellow-green to reddish, usually with two dark body spots; eggs are round; fine webbing may be visible.

Prevention

Reduce dust; water plants adequately; inspect leaf undersides; avoid unnecessary broad-spectrum insecticides; isolate infested transplants.

Management

Hose leaf undersides; remove badly infested leaves; use insecticidal soap or horticultural oil. Ensure contact and repeat per label because eggs survive.

Adults chew numerous small shot holes in leaves; seedlings can be stunted or killed. Some larvae feed on roots.

Favored By

Warm sunny weather, young seedlings, nearby weeds or crop residue, and repeated planting of susceptible crops.

What It Looks Like

Tiny (about 1/16–1/8 in), shiny dark or striped beetles with enlarged hind legs that jump when disturbed.

Prevention

Use row cover immediately after planting; remove weeds and residues; rotate crops; plant vigorous transplants or delay planting where practical.

Management

Remove cover at flowering when pollination is needed; use labeled kaolin clay or insecticides only when feeding threatens establishment.

For Corn, Sweet: Reviewed Research Library baseline; local occurrence and treatment timing vary.

Night-feeding caterpillars sever seedlings at soil level; climbing species also feed on foliage and fruit.

Favored By

Weedy ground, plant residue, green manure, and recently converted sod; small transplants are most vulnerable.

What It Looks Like

Smooth, stout, gray, brown, green, or black caterpillars, often striped or spotted; curl into a C when disturbed.

Prevention

Remove weeds and residue before planting; till before planting and in fall; use compost rather than fresh green manure; place collars around transplants.

Management

Search soil near damaged plants at dusk and handpick; treat small larvae with a labeled biological or insecticide only when damage is active.

Adults feed on many crops and flowers and may transmit bacterial wilt; larvae (southern corn rootworms) attack roots.

Favored By

Warm regions, abundant weeds, corn or cucurbits, and successive host crops.

What It Looks Like

About 1/4 in, yellow-green beetle with 12 black spots; dark head and long antennae.

Prevention

Use row cover on young cucurbits; rotate crops; control weeds; remove residue; plant robust transplants.

Management

Handpick or vacuum; monitor flowers and seedlings; use labeled insecticides only when feeding is severe, protecting pollinators from exposure.

Adults skeletonize leaves and eat flowers and fruit; larvae are white grubs that feed on turf roots.

Favored By

Sunny irrigated turf, moist soil during egg laying, and abundant favored ornamentals or fruit crops.

What It Looks Like

Metallic green adult about 3/8 in with coppery wing covers and white hair tufts along abdomen; larvae are C-shaped white grubs.

Prevention

Choose less-preferred plants; reduce unnecessary midsummer lawn irrigation; remove attractive, damaged fruit; do not use beetle traps near valued plants.

Management

Handpick into soapy water in early morning; protect high-value plants with netting; use labeled products carefully and avoid spraying open flowers.

Larvae feed in corn ear tips and bore into tomato, pepper, bean, and other fruit, contaminating produce.

Favored By

Warm weather, late plantings, continuous flowering hosts, and moth migration from southern areas.

What It Looks Like

Variable green, tan, pink, or brown caterpillar with stripes and tiny dark spines; adult moth is tan with a dark spot.

Prevention

Plant early where appropriate; use tight-husked corn cultivars; remove damaged fruit; monitor moth flights and eggs; conserve natural enemies.

Management

Handpick from tomatoes and peppers; use Bt or spinosad on small exposed larvae where labeled; treatments are ineffective after larvae enter ears or fruit.

Adults and nymphs pierce fruit and vegetables, causing dimpling, corky spots, discoloration, and malformed produce.

Favored By

Warm seasons, wooded edges, diverse fruiting hosts, and nearby overwintering structures.

What It Looks Like

Shield-shaped mottled brown bug about 5/8 in; alternating light-dark marks on abdomen edge and white bands on antennae.

Prevention

Remove weeds and alternate hosts near production where practical; use fine netting; seal buildings to reduce overwintering; conserve egg parasitoids.

Management

Handpick or knock into soapy water; use traps for monitoring rather than control; apply labeled insecticides only when repeated feeding threatens crops.

Microscopic roundworms induce root galls, restricting water and nutrient uptake and causing stunting, yellowing, and midday wilt.

Favored By

Warm sandy soil, susceptible crops, contaminated transplants or soil, and repeated host crops.

What It Looks Like

Microscopic; diagnosis relies on swollen knots or galls on roots, often with a weak uneven crop canopy.

Prevention

Use clean transplants; grow resistant cultivars; rotate with poor hosts; solarize soil in hot climates; add organic matter and clean tools.

Management

Remove heavily infested roots; use resistant crops and rotation over multiple seasons; soil-applied products are limited and must be labeled for home gardens.

Larvae chew seeds, roots, and underground stems or tubers, causing poor stands and holes in potatoes and root crops.

Favored By

Recently converted sod or weedy ground, cool moist soil, and high organic matter.

What It Looks Like

Slender, hard-bodied, shiny yellow to brown larvae with three pairs of small legs; adults are click beetles.

Prevention

Avoid planting susceptible crops immediately after sod; till to expose larvae; control grassy weeds; use bait stations before planting to assess risk.

Management

Trap with buried potato or carrot pieces and remove larvae; rotate to less susceptible crops; rescue treatments after planting are generally ineffective.

Browse foliage, buds, flowers, and fruit; damage often occurs high above the ground with ragged torn stems.

Favored By

High deer density, drought or winter food shortage, gardens near woods, and unfenced plantings.

What It Looks Like

Large hoofed mammal; cloven tracks and pellet droppings; browsing can reach roughly 6 ft.

Prevention

Install an 8-ft deer fence or properly designed electric fence; use cages and netting; choose less-preferred plants while recognizing none are deer-proof.

Management

Exclude first; rotate repellents labeled for edible crops and reapply after rain; protect young trees with guards. Follow local wildlife laws.

Consumes large amounts of vegetables and can flatten plants; burrows may undermine beds or structures.

Favored By

Gardens near field edges, brush, sheds, stone piles, and accessible fence bottoms.

What It Looks Like

Large stocky brown-gray rodent with short bushy tail; wide burrow entrances and tracks with four front toes and five rear toes.

Prevention

Use sturdy 3-ft wire fencing with 12 in buried or bent outward; add an outward electric wire; remove brush and block access under structures.

Management

Exclusion is most reliable; harassment and repellents have limited persistence; trapping or euthanasia must comply with state and local law.

Pull seedlings, eat newly sown seed, peck ripening fruit, and damage corn or berries.

Favored By

Visible seed, ripening fruit, nearby roosts, and unprotected beds or small fruit plantings.

What It Looks Like

Species vary; identify by tracks, droppings, peck marks, missing seed, and time of activity.

Prevention

Use secured bird netting with openings that cannot entangle wildlife; row cover seedlings; reflective or moving deterrents work best when varied.

Management

Exclude during the vulnerable period; harvest promptly; avoid toxic baits. Federal and state protections apply to many bird species.