Since 1996, cotton farmers have had access to Bt technology, which they say has resulted in higher yields, fewer trips with the sprayer and increased beneficial insects in their fields.
How has this happened? First, here's a quick refresher on Bt technology. When an insect consumes a plant, like cotton, with Bt proteins, the proteins enter the insect's body and kills them within the gut. As a result, farmers can skip reactionary spraying, which happens after insects have already eaten away at leave and fruit, damaging yield. Instead, the protection is within the plant, which both reduces the need to spray and reduces the likelihood of yield losses. It's a big change. Before the introduction of Bt cotton technology, insect damage could be severe, causing many farmers to spray multiple times to preserve their cotton crop.
It's caused three big changes in cotton production:
- Increased yield due to decreased plant stress. Since the plant isn’t constantly dealing with defending itself from repeat feeding insects, it can focus on making a fruit and making more of it. “Twenty years ago our biggest challenge in cotton was insect pests,” says Gaylon Morgan, Texas A&M AgriLife Extension cotton agronomist. “Bt provides a more consistent protection which helped cotton plants reach their full yield potential.”
- Decreased trips across the field with insecticides. This saves time and money from fuel and insecticide. “We’re not spraying ten times for caterpillar pests anymore,” says David Kern, associate professor of cotton and Jack Hamilton Regent’s Chair in cotton production at Louisiana State University. “They’ll spray maybe once or twice, but in many areas they rarely spray anymore.”
- More beneficial insects. The reduction in sprays means you have more insects, especially beneficial ones, in your fields. Keeping beneficial insects doesn’t just make you sound good to environmentalists; it also can help you control some of the more troublesome pests in your fields. Beneficial insects make sure there is competition for new flights of moths, which decreases the likelihood of an epidemic, for example.
After 20 years, do farmers have resistance? Maybe, maybe not. The issue of resistance is tricky in cotton. Currently, there is no confirmation of an insect being resistant to traits in the crop, says Robert Bowling, Texas A&M Extension entomology specialist. “Even though we have some worms surviving the Bt protein at this point, we can’t say they’re resistant," he adds.
Bowling says in cases where worms get through its more likely some varieties or plant parts might not express Bt as much. Some insects, such as bollworm, are less susceptible to the Bt trait. These pests can exploit weak varieties or plant parts, and once the insects grow bigger, they are better able to survive the Bt protein.
Cotton farmers still have many challenges. Resistant weeds challenge farmers’ ability to grow a hearty, successful crop. Over the next 20 years, farmers can expect to see more advancement in weed-fighting technology, including varieties like Monsanto's Xtendflex, and Dow AgroScience's Enlist weed control system.
Remember, with any technology continued stewardship is essential. “Environmental stewardship is important," Bowling says. "Without it, we could be forced back to broad-spectrum insecticides."
Have you used Bt cotton? What have you seen in your fields? Let us know in the comments.