Corn hybrids having a long, tight fitting shuck appear to suffer less damage than those with loose shucks. Find more gardening information on Gardening Know How: Keep up to date with all that's happening in and around the garden. Repeated sprays at three to five day intervals until 90% of the silks have wilted should give a high percentage of worm free ears during early and midseason. The corn earworm is a white, green, brown, or red caterpillar with spines. Special attention should be given to late planted fields and fields with green silks. Initial corn earworm sprays are applied when silks first emerge. Green lacewings and soldier beetles are also effective answers to how to kill corn earworms. Handpicking, insect traps, and drops of suffocating mineral or vegetable oil are the least invasive controls for corn earworms. This small parasitic wasp -- 1/50th inch -- attacks the eggs of leaf eating caterpillars. Considering EVERY buyer of sweet corn from my farms asks if it is GMO, sweet corn can NOT be grown if it is genetically modified and then sold by the farmer. The larvae often destroy the silks before pollination is complete. Figure 1. Once earworm has become established within the ear, control is impossible. New Varieties Bt, Bacillus thuringiensis, or a dusting of Sevin will slow heavy infestations. They demand ears with worms and it’s fine by me. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. 2. In the fall, get rid of earworm’s overwintering pupae by turning the soil and exposing them to freezing temperatures. Genetically engineered corn, each kernel producing its own pesticide, was developed with corn earworms in mind. Runoff from these sprayings contribute to watershed and water table contamination while the spray itself decimates beneficial insects. Got chickens? Pest Problem Solver Prior to tassel emergence, walk your fields a couple of times per week to look for feeding from either European corn borers or fall armyworms. Your email address will not be published. Worms frequently follow leaves down the ear, leaving excrement and settling into kernels well in from the tip. Pheromone traps need to be examined twice a week for corn earworms beginning in early June to determine moth activity and the need to spray. 1. Extensive damage is often found at the ear’s tips, where the worms devour kernels and foul them with excrement. Attract to the garden beneficial insects such a green lacewings and parasitic wasps—braconid, chalcid, ichneumonid, and trichogramma—which attack earworms. In areas where this insect survives the winter, pupae hibernate in the soil. A spray pressure of 30 psi or higher is recommended. So I would refute the idea that a sweet corn that contains an earworm is not GMO. This includes selecting the best varieties and planting dates. Till your soil fall and spring to expose the pupae to wind, weather, birds and other predators. Earworms spend a relatively short period of their life feeding in a site that can receive an adequate insecticide application. There is growing concern that corn earworm in some regions of the Midwest has developed resistance to this class of insecticides. Their hind wings are white with white borders. Corn earworm moths are most active during evening and night. This fierce predator stuffs its 3mm length with thrips, spider mites and more! As odd as it may sound, to prevent corn earworms from gaining entry to the ears, try placing clothespins where the silk joins the ear. Tip: When using mineral or vegetable oils to suffocate feeding larvae at the ear’s tips, include a botanical insecticide in the oil as an added punch. If you suspect your former corn patch might harbor corn earworm pupae, try broadcasting. The oil will suffocate the worms. Corn, both sweet and field varieties, is one of the most popular plants in gardens all over the country. If you till the soil in the fall after the corn season and again in the spring before you plant, you can unearth the pupae, and the weather will kill them before they can hatch. Economic Threshold: When tassels emerge and silks are still green, numbers of corn earworm moths captured in pheromone traps will determine the frequency of insecticide applications. Trichogamma is an egg parasite wasp that lays its eggs inside the eggs of the earworm. They are hard to see with your naked eye. Corn earworm is potentially the greatest threat to sweet corn production in Kentucky. Early in the season, corn earworms feed on the leaves of the plants, leaving ragged edges. Corn that matures early will have fewer problems. Green lacewings and soldier beetles are also effective answers to how to kill corn earworms. Draw corn husks closed with a rubber band so that earworms can not enter. It is cheaper and has worked great. Some customers at our farm stand are educated enough to know that if an ear has earworm damage it means it’s non-GMO or sprayed with insecticide even though there are organic controls. Continued vigilance is needed. The Heliothus zea has the distinction of being the most destructive corn pest in the United States. They can be olive green, tan, or dark reddish brown. Monitor the trap frequently and change the lure every two to three weeks. Although variable in color, corn earworm larvae feel rough to the touch. Another part of a sound IPM program is to choose some of the new fresh market Bt varieties, he says. Privacy Policy. The corn earworm is also a serious pest of cotton where it is known as the cotton bollworm. Similar to Bt field corn, Bt sweet corn has been genetically engineered with a protein that kills certain caterpillars. Yet, in ecological or organic production of sweet corn, achieving worm-free corn is one of the most difficult challenges. You are more likely to notice the moths in the … “They will be coming, so be prepared,” says Rick Foster, a professor in the Department of Entomology at Purdue University. The silks turn brown after pollination. CAUTION! Corn earworms generally complete their development in 14 to 16 days. As moths, corn earworms are great travelers. Just because you had them well-managed the previous season doesn’t mean they won’t glide back in on the first warm breeze come springtime. They also excrete brown droppings that leave corn ears dingy and unappetizing. The oil will suffocate the worms. Once earworm has become established within the ear, control is impossible. Corn hybrids having a long, tight fitting shuck appear to suffer less damage than those with loose shucks. Resistant varieties include Aristogold, Calumet, Country Gentleman, Iona, Seneca, Chief, Senecat Scout, Silver Cross Bantam, Staygold, and Victory Golden. It is about 1½ long. Control in corn is 50-100% successful. Just because you had them well-managed the previous season doesn’t mean they won’t glide back in on the first warm breeze come springtime. Let them free range over the tilled area, and they will gladly eat as many insects as they can find! If you get an infestation of corn earworm and do not get it under control immediately, you are likely to lose your entire harvest. Each year they migrate from warm southern areas back to northern states where they are subject to winterkill. Figure 2. This includes selecting the best varieties and planting dates. A few years back with GMO BC0805, I had 90 out of 100 ears of GMO sweet corn with earworms in them. There are, however, ways to prevent corn earworms from wreaking havoc in your corn patch. Extension   /   I used a GMO Sweet corn for several years, starting with something like 935? Some field failures have been reported. Don’t let those devilish insects ruin the pleasure of raising your own sweet corn. 5. You can usually see the corn silk appear roughly two months after the corn seeds have germinated. “Late in the season, when earworm pressure is high, sticking pretty closely to a conventional spray schedule is a good idea because sprays alone often don’t give the level of control desired when populations are extremely high, but the combination of sprays with the Bt variety will give superb results.”. However, many different pests can ruin an entire crop, and the corn earworm is one of the worst. There are generally four generations each year, however, overlap is great and adult moths that can lay eggs may be present in significant numbers throughout most of the growing season. Use oil on corn only after the silks have begun to turn brown.