The Return of Corn Rootworm

Corn rootworm used to be a prominent pest before the benefits of crop rotation were understood and put into practice. Breaking the rootworm life cycle by avoiding corn on corn was an effective control measure that combatted the insect eggs’ ability to overwinter in corn and re-infest the next crop. While crop rotation is still effective, there’s now Poncho^® 1250 seed treatment. If you select a hybrid with built in rootworm protection, then make sure you use Poncho 1250 seed treatment on your refuge acres to offer a helping hand.

As the economics of growing corn improve, growing consecutive corn crops in the same field is a very tempting prospect. To be effective, corn rootworm protection has to begin before the seed hits the ground – whether through crop rotation, seed treatment or corn hybrids with built in rootworm protection.

Poncho 1250. More than Corn Rootworm Protection.

Poncho 1250 is the only seed treatment with protection against corn rootworm, in addition to all major early season corn insect pests. Poncho 1250 also provides a smart resistance management choice by protecting all refuge acres from corn rootworm. If you select a hybrid with built in rootworm protection, then make sure you use Poncho 1250 seed treatment on your refuge acres to help maintain the effectiveness of corn rootworm control throughout your field.

In addition to corn rootworm control, Poncho 1250 is also recommended for later season control of all major insect pests – beyond the five-leaf stage of corn – and areas with higher overall insect pressure.

Corn Rootworm 101

"Scout for corn rootworm every year." That's the bottom line from field crops entomologist Tracey Baute, Ontario Ministry of Agriculture, Food and Rural Affairs. "Corn rootworm is the number two pest in terms of its ability to develop resistance, second to the potato beetle."

"If you grow continuous corn on a regular basis, scout in August to check for the presence of adult rootworm," says Baute. "Adults give you a good indication if enough eggs will be laid to need protection in the next crop year." The prominence of the pest depends on the year. So for 2008, overall corn rootworm levels were lower as the frequent rains didn't help larvae survival in the soil.

When you expect a heavier infestation, Baute acknowledges that seed treatment (like Poncho 1250) is a good tool – and one that must be used wisely. "Corn rootworm has adapted to crop rotation and has the ability to adapt to control products," she says. "Growers need to help keep products in the marketplace with responsible use, rotating with different chemistry when you can as well as rotating crops."

Multiple crop rotations – more than just corn/soy – are in fact what's keeping a rootworm variant out of Ontario fields. The variant lays eggs in soybeans and other crops, and the eggs hatch the following year and can survive if a corn crop is planted in the same field that year. "We're fortunate that we don't have to change our management strategy because our diverse crop landscape is making it very hard for us to find the variant in Ontario."