Golden Bantam Sweet Corn

A virus spread by the beet leafhopper (*Circulifer tenellus*), mainly a problem in the western US — California, Arizona, Colorado, Idaho, New Mexico, Utah, and Washington. It has a broad host range, infecting beets, tomatoes, peppers, beans, and cucurbits. Infected plants develop curled, thickened leaves with purple-tinged veins on the undersides, stunted growth, and fruit that ripens prematurely. The leafhopper transmits the virus while migrating: it lands and briefly probes plants, and a single feeding of just a few seconds is enough to infect.

Triggers: Driven by leafhopper migration, not weather directly. The bugs overwinter in foothill weeds and head for gardens in late spring once the wild vegetation dries up. Hot, dry years push more of them into populated areas. Symptoms show up 7-14 days after a single leafhopper visit — and a single bite is all it takes.

Risk fades when: Migration peaks in late spring; once the main wave passes, transmission risk drops sharply. The virus doesn't hide in soil or plant debris between seasons, so risk resets each year.

A soil-borne fungus (*Sclerotium rolfsii*) that attacks plant stems right at the soil line during hot weather. It hits over 500 different plant species. Two telltale signs to look for: white fan-shaped fungal growth on the lower stem, mulch, and soil surface, and tan-brown spherical sclerotia (they look like mustard seeds) on infected tissue. Most active during sustained heat with humid conditions.

Triggers: Optimal at 86°F (30°C) soil and air temperature with humid conditions. Inactive below 70°F. Most damaging during sustained mid- to late-summer heat waves. It extends further north in warmer-than-normal seasons.

Risk fades when: Sustained cooler weather — highs below 80°F and overnight lows below 70°F for 5+ days — reduces fungal activity. The sclerotia (resting bodies) persist in soil for years, so resolution is seasonal, not curative.

Corn earworm is the same species as tomato fruitworm and cotton bollworm — a polyphagous caterpillar that bores into ears of corn through fresh silks, into tomato and pepper fruit, into lettuce heads, and into bean and pea pods. In sweet corn, losses can reach 50%. The species migrates north annually from southern overwintering grounds; in much of the northern US, it does not survive the winter when temperatures drop below 30°F.

Triggers: Overwinters as pupa in top 2-4 inches of soil where winter temps permit. North of I-70 (Illinois IPM): does not reliably overwinter — populations arrive via migration mid-July through September. Females prefer fresh corn silks for egg-laying; older silks rejected.

On Golden Bantam Sweet Corn: Insects feed from the ear tip into developing kernels.

Prevention: Encourage natural predators and harvest promptly when mature.

Risk fades when: In the North (above roughly 40 degrees latitude) the insect does not overwinter, so populations arrive only by summer migration and are wiped out by fall frost, resetting each year; in the South it overwinters as a soil pupa and pressure lasts longer (UMN VegEdge, Wisconsin Hort, Cornell IPM).

A seedling killer caused by several different fungi working together. It hits vegetables, flowers, herbs, microgreens, and cover-crop seedlings the same way — seeds rot before they emerge, or young seedlings collapse right at the soil line. Wet seed-starting mix and poor airflow in seedling trays are the classic conditions.

Triggers: Wet soil or starting mix, poor drainage, seedlings packed too tightly, contaminated trays or media, and stagnant air all favor damping-off.

Risk fades when: Drying the soil surface and improving airflow slows new spread. Collapsed seedlings don't recover, but the rest of the tray can be saved.

Northern corn leaf blight announces itself with lesions no other corn disease produces: long, cigar-shaped, grey-green streaks running parallel with the veins, which later dry to tan and can merge until whole leaves are killed. UMN Extension identifies the pathogen as Exserohilum turcicum, and notes that it overwinters on corn leaf debris, that several races exist which interact differently with different resistance genes, and that resistant hybrids are the primary control. The disease costs yield by destroying photosynthetic area at exactly the wrong moment. Peer-reviewed work reports losses of 30 to 50 percent in temperate regions during wet seasons, particularly where infection reaches the upper leaves by silking, and losses of up to 40 percent from infections two to three weeks after pollination. Infection needs free water on the leaf for roughly 6 to 18 hours at temperatures between about 66 and 80°F; lesions then appear in 7 to 12 days and produce new spores, so a wet spell early in the season compounds through the summer. Because the fungus overwinters on residue, corn following corn in the same ground is the classic mistake.

Triggers: UMN Extension: the pathogen is the fungus Exserohilum turcicum (syn. Helminthosporium turcicum); it overwinters on corn leaf debris; several races are known which interact differently with different resistance genes; use resistant hybrids; crop rotation and tillage practices may be helpful. Peer-reviewed literature: E. turcicum (teleomorph Setosphaeria turcica) causes cigar-shaped or spindle-shaped green-grey lesions on leaves which become necrotic and may coalesce into blight. It overwinters as mycelia and conidia on maize residues left on the soil surface; during warm moist weather new conidia are produced and carried by wind or rain to the lower leaves of young plants. Infection requires water on the leaf surface for 6 to 18 hours and temperatures between 66 and 80°F; lesions develop within 7 to 12 days and produce new conidia that spread the infection. Yield losses of 30 to 50 percent occur in temperate environments during wet seasons, particularly if infection is established on upper leaves by silking; infections 2 to 3 weeks after pollination cause losses up to 40 percent. Four major resistance genes are characterised - Ht1, Ht2, Ht3 and HtN - and races are classified by which of these they overcome, so resistance is not durable. Young seedlings are more susceptible than two-month-old plants.

On Golden Bantam Sweet Corn: Humid weather and dense foliage support foliar disease.

Prevention: Rotate crops, maintain airflow, and avoid overhead irrigation late in the day

Risk fades when: Lesions do not heal, and by the time they are obvious the infection cycle is already running. What matters is protecting the upper leaves through silking, since that is where yield is decided. For the home garden the practical controls are rotation and residue: the fungus overwinters on corn leaf debris, so do not plant corn where corn grew last year, and remove or bury the old stalks and leaves rather than leaving them on the surface. Choose resistant varieties, while knowing several races exist and races are defined by which resistance genes they overcome. Space plants for airflow and avoid overhead watering late in the day, since infection needs six or more hours of leaf wetness.

The Delia root-maggot complex includes the cabbage maggot (D. radicum) on brassicas and root crops, the seedcorn maggot (D. platura) on bean/pea/corn seedlings, and several other species. Larvae tunnel into roots, basal stems, and seeds, killing seedlings outright or creating tunnels that ruin root crops for market. A 2021 Oregon industry survey found 100% of root crop growers reported cabbage maggot damage; 44% with 10-25% yield loss.

Triggers: Overwinter as pupae in soil/crop residue. Adults emerge early spring (300-600 GDD base 40°F after Jan 1 in PNW). Cool moist soils favor egg survival; soil >95°F in top 2-3 inches kills eggs. Multiple generations per year. Seedcorn maggot attracted to decaying organic matter — high risk after fresh-incorporated cover crop.

Risk fades when: Cool, wet weather favors root maggots and damage is worst in early spring, dropping to its lowest in midsummer when soil temperatures above about 95 F kill the eggs; a late-summer flight can still injure fall root crops, so risk returns as weather cools (UMaine Extension, Wisconsin Hort, UNH Extension).

Aphids are soft-bodied sap-sucking insects that cluster on tender new growth. Most established plants tolerate moderate populations and will outgrow damage on their own, but aphids are the most important plant virus vectors in the garden, transmitting more than 100 plant viruses including potato leafroll, cucumber mosaic, and turnip mosaic. Honeydew excreted while feeding supports sooty mold growth and attracts ants that protect aphids from natural enemies.

Triggers: Optimal development at ~75°F (green peach aphid) per UC IPM Floriculture; melon aphid develops fastest above 75°F. Many species heat-intolerant above 90°F and crash in mid-summer. Soft new growth and over-fertilization with high N favor population buildup. Females give live birth parthenogenetically most of growing season — one generation in ~1 week under optimal conditions.

Risk fades when: Per UC IPM and Clemson HGIC, populations crash in mid-summer heat (>90°F) for many species, return in cooler conditions

Birds cause significant damage to ripening fruit (berries, grapes, figs, cherries), to newly-planted seeds, and to seedlings. Damage peaks during fruit ripening on berries and during seed-head ripening on sunflowers. Robins feed low on bushes; starlings feed in upper canopy; species and feeding patterns vary widely. Even partial damage opens entry points for diseases and insects.

Triggers: Damage seasonal — peak during fruit ripening (June-August in north). Dry years intensify damage as birds use fruit for water. Proximity to forest edges or harvested grain fields amplifies pressure.

Risk fades when: Risk is tied to each crop's ripening window - berries in June through August, corn at silking, sunflower at seed-head fill - so pressure fades once the vulnerable fruit or grain is harvested; netting or row cover during that specific window is the main protection (Oregon State Extension, EM 9286).

A corn-specific rust, not a generic rust model. Produces orange-brown pustules on corn leaves.

Triggers: Cool to mild weather, heavy dew, high humidity, and about six hours of leaf wetness all favor common rust development.

On Golden Bantam Sweet Corn: Humid weather and dense foliage support foliar disease.

Prevention: Rotate crops, maintain airflow, and avoid overhead irrigation late in the day

Risk fades when: Hot or dry weather outside the mild humid range reduces new rust infection.

Flea beetles are small (1/16-inch) shiny beetles that jump like fleas when disturbed. They chew small round 'shothole' or 'pinhole' damage in leaves and can destroy emerging cotyledons of broccoli or eggplant in 24 hours. Most species are host-family specific — crucifer flea beetle on brassicas, tuber flea beetle on potatoes, eggplant flea beetle on solanaceous crops.

Triggers: Overwinter as adults in leaf litter and field margins. Active at mid- to late-spring temperatures. Warm winter → higher next-spring populations (NC State). Hot dry conditions amplify damage on stressed seedlings.

Risk fades when: UMN: 1-2 generations in Minnesota, populations crash after mid-June