In western Kansas and Nebraska and the panhandles of Texas and Oklahoma, the corn rootworm is a big problem.
Over the years, as populations have steadily grown, plant varieties utilizing BT technology have been the best answers to combat the rootworm pest. It has been uniquely effective. That’s a source of concern for Spencer McIntosh, agronomist at Golden Harvest Seeds.
“Planting varieties with the BT trait is the most cost-effective tool we have and there has been a great deal of reliance on BT technology since it was introduced 15 years ago,” McIntosh says. “My concern is that there has been too much reliance on one technology and we are putting too much selective pressure on the corn rootworm.”
Corn rootworms are not really much of a problem in southeast and south-central Kansas, he says.
“Rotation is very important both for crops and for pesticides,” McIntosh says. “In recent years, we have seen some drop in the control we are getting with the BT trait. We need to take a look at going back to adding another insecticide in areas where there is heavy pressure.”
Soil insecticides over the top of BT varieties are available and were the tools most often used before the introduction of the BT trait.
Counter and Force are both still on the market and either is a good add to BT varieties to help assure that rootworm control is complete, he says.