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Protecting corn seedlings against early-season pests

Corn producers in Eastern Canada face a number of prominent early-season corn pests, including wireworms, white grubs, seedcorn maggots, black cutworms and sometimes early infestations of armyworms. Minimizing the impact of these pests on corn crops requires an integrated approach that combines a number of management practices, including proper crop rotations, conventional tillage and seed treatment.

Identify the pest

Wireworms, grubs and seed corn maggots are belowground feeders. They feed on the corn seed and roots, causing runt plants or sometimes for the seed to not germinate at all. Black cutworms and armyworms are aboveground feeders and cause defoliation. Cutworms also feed on the stem and have ability to cut the plant completely.

Saghir Alam, seed treatment product development manager for Corteva Agriscience, has a number of tips for producers to consider when scouting for pests in corn fields. First, he says, for belowground feeding pests like wireworm, grubs and seedcorn maggots, check for missing plants and stunted, or runt, plants in corn rows.

“Bait traps are also helpful to understand wireworm infestation level in the field,” Alam says. “Knowing and understanding of the previous history of the field is very important.”

For aboveground feeding pests, Alam says, regular scouting and monitoring of the fields after germination is critical.

“Check for patchy areas and hilly spots for any visual defoliation of the plants.”

Early-season prevention

To minimize the risks from early-season pests, producers should take an integrated approach to management. This includes following proper crop rotation recommendations, using good quality seed and conventional tillage practices.

“Proper crop rotations and conventional tillage can help to reduce the pest population build up by disturbing the life cycle of the soil pests,” Alam says.

However, he adds, seed treatments are the only effective way to control these pests. This is because if growers don’t use seed treatments, by the time they see the damage to the crop, it is already too late to control these pests and sometimes, under high pest infestation situations, growers will need to re-seed.

“Soil pests are patchy, hard to predict and also hard to scout when we compared to other foliar insect pests,” Alam says, adding that most of the time, foliar application of insecticides does not control early soil pests, because the pests don’t directly come in contact with foliar sprays. “Seed treatments are a very effective measure to control these soil and early-season corn pests.

“They are also very environmentally friendly in terms of application and use rates when compared to the foliar application to control the same pests.”

Lumivia, a new insecticide seed treatment for corn from Corteva Agriscience, is the first to contain chlorantraniliprole, the active ingredient belonging to a new class of chemistry called anthranilic diamides (Group 28).

Lumivia offers protection up to the V4-V5 leaf stage against early season insect pests, such as wireworms, cutworms, white grubs, seedcorn maggot and armyworm. It offers a new mode of action that protects seedlings, providing uniform and healthy stands to maximize yield potential.

“Lumivia insecticide seed treatment has a very unique mode of action: it impacts insect behaviour by impairing muscle function,” Alam says, explaining it does this by causing the insects to release all their muscle calcium, which is used to provide energy when insects like to feed or move. “Insects exposed to Lumivia corn seed treatment stop feeding immediately; they become lethargic, paralyzed and eventually die.

“Corteva’s recommendation to all farmers and workers while handling the treated seed with Lumivia during planting is to follow the best management practices developed by CropLife Canada,” Alam says. Best management practices to help minimize dust exposure can also be found on the Health Canada website (www.healthcanada.gc.ca/pollinators).

Above all, a multi-faceted approach to combating early season corn pests is important, and growers should speak to their agronomist about the best management practices when handling treated seed and dealing with insect pests.