Retain the refuge
There's nothing like news of a 100-bushel-per-acre yield spike to pop up any postlunch dozing heads at a farm meeting.
This snooze-snapping data came from a 2006 University of Illinois (U of I) trial in which a corn rootworm- resistant hybrid outyielded a hybrid protected from corn rootworm with a soil-applied insecticide by nearly 100 bushels per acre.
This was just one trial, and other studies show lower responses. Still, yields of corn rootworm-resistant hybrids edging those of conventional hybrids treated with soil insecticides by 50 to 60 bushels per acre are becoming more common in research plots and in farmers' fields where corn rootworm is a problem.
Farmers also have more choices than ever before. Syngenta Seeds has its Agrisure RW product. Monsanto is marketing YieldGard Rootworm, while Pioneer Hi-Bred International and Dow AgroSciences sell Herculex RW. These products are also available in stacks. All use a Bt protein to control corn rootworm.
No insect control is bulletproof. However, corn rootworm-resistant hybrid failure is uncommon, and the resulting rootworm control has prompted farmers to snap them up faster than cold beer at a sultry summer doubleheader.
"We're experiencing a revolution we haven't seen since the 1950s, when soil-applied insecticides were first used to control insects," says Kevin Steffey, U of I Extension entomologist.
There's a catch, though. You have to plant a refuge of non-Bt corn on 20% of your field.
It's a pain. Planting a refuge takes time when you can least afford it. It's also extra hassle applying a soil-applied insecticide.
Still, farmers have done a great job of planting refuges, with compliance rates over 90%. But there's a concern farmers may reject refuges in light of the eye-popping yields and booming corn economics.
"Individuals have told me that planting a refuge will be a tough decision for them," says Mike Gray, U of I Extension entomologist. "When you look at 50-, 60-, even 100-bushel yield differences, this is a tough, tough issue."
There are some good long-term reasons, though, why you should retain a refuge.
In any population, there exists a handful of insects resistant to a control. A variety of controls that farmers mix up in the landscape or use from year to year -- such as corn rootworm-resistant hybrids and soil-applied insecticides -- prevents these populations from growing. Reliance on just one control -- which would be the case if farmers nixed refuges on a large scale -- would nudge resistant populations to develop. In time, resistant insects could render the transgenic technology ineffective.
"The reality is that around 500 insects are resistant to pesticides," points out Tami Craig Schilling, Monsanto public affairs director. "Even though YieldGard and other Bt technologies are highly effective at controlling corn rootworms, they are controlling living organisms, and we still need to take caution. We can get a false sense of security -- since corn prices are high and the technology is working -- that we don't need to plant a refuge."