Higher Crop Returns Don’t Negate Need for Thoughtful Pest Management

When corn prices suddenly rose dramatically in 2007, Illinois researchers reported that some farmers were willing to do anything to increase their yields. Many of them used products to combat pests that they didn’t even have.

I’m not trying to single out corn farmers. Anytime crop prices rise, the desire to protect the crop is only natural. If one pest management technique works well, adding another to it should help more, right?

Although that reasoning seems logical—and might bring short-term success—ultimately it can turn those gains into losses as insect populations begin to develop resistance to the techniques. For instance, farmers who plant transgenic crops must plant a certain percentage of their crops in a non-transgenic “refuge” field. Although yields in the refuge field are typically lower than those in Bt fields, the refuge field maintains a certain percentage of insects that are susceptible to the Bt toxin.

According to Kevin Steffey, entomologist at the University of Illinois, resistance is a normal adaptation to a selective stress. Integrated pest management is designed to delay resistance by using the right management techniques for the right pest. Pesticides or other techniques are based on insect populations and biology. Farmers don’t spray for a pest that isn’t in their field. Depending on the habits of the insect, farmers may have to time applications to coincide with the insect’s biological cycle. Pecan nut casebearer, for example, lives outside the pecan shell for only a few days, giving the farmer only a short window to use an insecticide effectively.

Steffey cites the major crop losses of the 1960s, when pests became resistant to DDT and many of the organochlorines that were impressively effective at first. Some growers, he says, are treating Bt crops as the new DDT—a magic bullet that will never outgrow its usefulness.

However, he says, ignoring principles of insecticide resistance could not just be damaging; it could be devastating.

In fact, that’s what some of the members of the Mid-South Entomologist group warned cotton farmers about this week at the Beltwide Cotton Conference. Cotton farmers have had to spray Bollgard II cotton since 2008, when specialists and consultants began spotting bollworm larvae in the lower half of the cotton plants. To combat the damage from increasing bollworm populations each successive year, growers started adding pyrethroids to the insecticide mix for Bollgard II cotton.

“Since 1988, we have been monitoring for resistance to pyrethroids,” said B. Rogers Leonard, entomologist from LSU AgCenter. “From the trend we’re seeing, we’re going to get to a point where pyrethroids aren’t going to work.”

Leonard and Mississippi State University colleagues Angus Catchot, extension entomologist, and Jeff Gore, assistant research professor, recommended that growers follow the refuge requirements.

For more information about the source of the idea for this article, read “Do Higher Corn Prices Mean Less Adherence to Ecological Principles?

Other blog posts on Bt resistance:

Researchers Validate Resistance Management Practices for Bt-crops

Are Bt Crops a Silver Bullet or a Looming Disaster?

One Response

  1. Some good points..

    I’ve found the Yield Data Center site to be a good resource for crop yields information

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: