Sweet Corn Pest Management

Sweet Corn’s Insect Pests

This popular vegetable can be popped, baked, boiled, canned, chilled, or grilled. Sweet corn—one out of Florida’s four most valuable vegetables—grows on nearly 30,000 acres throughout the state.

While people may think sweet corn is widely grown in more rural states, Florida ranks first nationally in sweet corn production. Because of sweet corn’s economic importance, farmers should understand its most prominent pests.

Insect Pests

Corn Earworm

Corn earworms, once considered the primary pest of corn, can infest 100% of untreated ears throughout south Florida. The moths feed on the plant’s nectar, and young larvae eat the ears, husks, and leaves.

Scouting the fields twice a week can help control corn earworms. While birds and natural insects serve as enemies to this pest, they cannot prevent yield loss—birds can also cause more damage than these pests when they feed on kernels. Some genetically modified varieties are available that can help prevent damage caused by corn earworms.

Fall Armyworm

Fall armyworms are the most important—and destructive—sweet corn pest in Florida. As adults, fall armyworms, which suck on nectar, deposit up to 200 eggs in the plant. These eggs release larvae in only three to four days. The newborn pests then eat the outer leaves and move to consuming inner leaves, silk, and ear tips, damaging kernels and cob.

Monitoring the fields once a week is necessary prior to the ear stage of development. Destroying the larvae that are pushed from the whorl will help to protect the ear shoots and flag leaves. Natural insect enemies and birds can help during the germination stage, but chemical controls and granular formulations seem to be most effective.

Lesser Cornstalk Borer

Like corn earworms, the narrow-winged moths suck on nectar and other juicy sources found in the plant. The larvae, which develop from 17–42 days, burrow and eat the corn stem, disabling the plant from growing marketable ears.

Pheromone and backlight traps can be used to monitor adults, as adults are easy to see in the field. Since natural enemies are not a good control, cultivating the field a few weeks in advance of planting can help.

For more information on growing crops in the state, please visit the 2013–2014 Vegetable Production Handbook for Florida, which includes the chapter Sweet Corn Production in Florida.

Adapted and excerpted from:

M. A. Mossler, “Crop Profile for Sweet Corn in Florida” (CIR1233), UF/IFAS Food Science and Human Nutrition Department (rev. 03/2014).

G. S. Nuessly and S. E. Webb, “Insect Management for Sweet Corn” (ENY472), UF/IFAS Entomology and Nematology Department (rev. 02/2014).

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