Refuge corn? What’s that? I’ll show you! No corn doesn’t need to take refuge in some kind of crop refugee camp, but it can act as a safe haven for pests that like to eat my crops. Why would I want pests to eat my crops?
What is Refuge?
European corn borer, Ostrinia nubilalis Photo by Keith Weller. (Photo credit: Wikipedia)
Refuge plants are needed to mitigate the possibility of pests like European corn borer and corn rootworm becoming resistant to the Bt traits in corn plants. As you may already know we plant quite a few acres of biotech crops. Bt is a protein that is effective against very specific pests. A refuge corn plant has no Bt trait. The idea behind refuge is the pests that feed in the refuge will mate with a pest that may have not been killed by the Bt crop. The progeny of those adult moths will then not be resistant. This process is key to the longevity of the technology.
This plant in a field of mostly Bt plants becomes a safe place, or refuge, for a pest like corn rootworm to feed. Up until about two years ago refuge in corn fields was required to be planted as a separate block accounting for 20% of the crop either in the same field or in a field within a particular proximity to the Bt corn. Now we are able to buy corn with refuge as low as 5% mixed into the bag of seed before planting. I happen to like this idea because it is a way to avoid any free riding farmers who think they can plant all Bt and no refuge. Even worse would be utilizing the same Bt toxin year after year especially while growing continuous corn an not breaking the pest life cycle by rotating to a crop like soybeans. Mike Gray from University of Illinois offers a great look at this problem in “Western Corn Rootworms and Evolution of Resistance to Bt Hybrids.” One thing farmers must not forget is that no matter the production method from organic to biotech we must rotate not only our crops, but the methods by which we manage pests, weeds, and disease.
Of course now we also have stacked traits which means we can have more than one type of Bt expressed in a plant. If we only have one mode of action against a pest, or weed or disease for that matter, we are inevitably speeding up the selection process for resistance by relying on only one tool. But if I’m planting stacked traits of 2 or 3 Bt proteins the odds of a pest taking a bite of corn, not dying, and becoming immune to all 3 proteins are incredibly small.
Earlier this week Dad and I walked a few varieties of corn with one of our seed reps. I knew we were walking an area where the corn we planted was Refuge in a Bag or RIB. See the lone totally brown stalk of corn in the center of the picture? I guessed that stalk was a refuge plant because it obviously was further along in maturity than all the surrounding corn which is still green above the ear. It just so happens that the variety of corn we were looking at has a white cob instead of the more common red cob. Wouldn’t you know the all brown plant showed us it had a red cob meaning I correctly spotted a refuge corn plant in the middle of a bunch of Smartstax (multiple Bt events) plants! If you have a year with a lot of pest pressure you can easily spot the refuge plants because they likely will have lodged or shown other symptoms of pest feeding that won’t be exhibited by the other plants.
A lot of you who follow this blog will know that we raise popcorn. There is no GMO popcorn so you might be wondering how our popcorn is protected against these pests. We also raise a lot of a special type of field corn called waxy. Waxy is generally not GMO either because it’s a relatively small market. This means no Bt producing popcorn or waxy on our farm. All of our corn and popcorn seed arrives on the farm treated with Poncho. This seed treatment helps the crop stave off pests. A side benefit of the many acres of Bt corn planted in the US each year is that crops like my popcorn and waxy benefit from the greatly reduced pressure from the target pests. This reduces the need to spray multiple times during the growing season.
Until 2012 we ran liquid starter fertilizer at planting along with the soil applied insecticide Capture. When we bought a new planter for the 2012 season we did not equip it with any liquid application system meaning we are no longer using the additional insecticide application from Capture. Less pesticide applied, and less expense out of our pockets. So far we think we are doing just fine without the starter or insecticide. Between seed treatments and Bt it’s very rare now that we will come back during the growing to apply insecticide with a sprayer or airplane. And if we do it will be for a pest not controlled by these other methods. That’s fuel, water, pesticide, machinery, and labor we don’t need to buy or hire out. That’s winning on several levels in my book.
