Fifteen years ago, the transgenic gleam that burned in the eyes of agricultural scientists for ages became reality. That's when Roundup Ready soybeans and Bt corn debuted. These products quickly nixed weeds and European corn borer. (ECB) They blazed the path for numerous traits that today deter over a dozen insects and nearly any weed in your fields. By 2010, USDA Economic Research Service data shows 93% of U.S. soybeans and 70% of U.S. corn planted were herbicide-tolerant varieties. Meanwhile, Bt corn jumped from 1% of corn acreage in 1996 to 63% in 2010.
They've turned the Integrated Pest Management (IPM) focus of first inspecting, identifying, and, if necessary, treating pests, on its head. “Integrated Pest Management (IPM) is in a different world,” says Mike Gray, University of Illinois (U of I) Extension entomologist. “Planting Bt corn is now standard operating procedure. We have moved into a period where IPM stands for Insurance Pest Management.”
At the 2010 U of I Corn and Soybean Classic, Illinois farmers responded to the question: Would you plant a Bt hybrid for corn rootworm or ECB control knowing damage levels will be low? Seventy-five percent or more answered yes at several locations.
Why? Well, traits work. An analysis authored by Bill Hutchison, University of Minnesota entomologist, and 17 other entomologists showed Illinois, Minnesota, and Wisconsin farmers reaped $3.2 billion over 14 years by planting ECB-resistant corn.
Interestingly enough, farmers in these states who did not plant Bt hybrids garnered $2.4 billion of those benefits. The seed with the Bt traits costs more to plant with the tech fees, says Gray.
“If your neighbor planted Bt corn and suppressed corn borer and other insect populations and you didn't, it had a double benefit for you,” says Gray. “It controlled corn borer for both of you and you didn't have to pay for it. This caused entomologists to scratch their heads.”
So Why Plant It?
Doing so helps ensure insect control. Although ECB numbers are almost nil in some areas, there were pockets in western Illinois and eastern Iowa where ECB attacked nontransgenic corn in 2010.
In other cases, traited hybrids are the only game in town. A follow-up question at the 2010 U of I Corn and Soybean Classic asked if farmers could access high-yield hybrids with no Bt traits. Between 40% and 55% replied they could not.
“Increasingly, our program is tied to traited stacks,” says Gray. “There is no reversing that pattern unless resistance develops and becomes widespread.”
So far, resistance hasn't been a problem. When Bt corn hybrids first emerged in 1996, federal regulators and industry agreed for 20% refuges of non-Bt corn to accompany Bt plantings. This practice continued when corn rootworm-resistant hybrids were launched in 2003.
That hasn't been the case in weeds. Weeds that have evolved resistance to glyphosate and other herbicide modes of action are spreading.
“The perception of the grower is not to worry about it, because there will be another herbicide or genetic trait/herbicide combination that will effectively resolve the problem,” says Mike Owen, Iowa State University Extension weeds specialist.
There are herbicide-tolerant stacks on the market and coming down the pike. SmartStax, an eight-way trait stack containing glyphosate and glufosinate tolerance, was launched in 2010. Coming in the future include traits offering tolerance to 2,4-D, ‘fop’, dicamba, and HPPD-inhibitor herbicides.
If each trait is used repeatedly with no other modes of action, though, weeds will inevitably resist them.
“With herbicide-tolerant crops, it's not just SmartStax, but stacking smart,” says Jayla Allen, product development manager for Bayer CropScience. “Stacking everything together gives growers options. It's great for seed companies in that they can manage their varieties and breeding programs. But if you have volunteer corn going into soybeans, you need to make sure to have the solutions to control volunteer corn the next year.”
Click on the images below to view a larger PDF with 16 points and developments to keep in mind about traits as you make future cropping plans.