Bollgard II will be tough on worms

Farmers are about to enter the wormless era. With Bollgard II due out this year, farmers can concentrate on whether to spray for pests such as thrips and bugs, says a North Carolina State University entomologist.

In tests at four North Carolina locations in 2002 during a heavy worm year, Bollgard gave researchers almost complete control of bollworms, John van Duyn, North Carolina State Philip Morris professor of entomology, told a group of growers at the recent Southeast Cotton Conference sponsored by the Southeast Farm Press. “We are entering the bug era of pest management.”

The new Monsanto technology contains two Bt toxins, Cry1Ac plus Cry2Ab. Together, the toxins express high levels in the plant throughout the season, including the flowering parts. Monsanto received full regulatory clearance for Bollgard II in 2003. Limited seed supplies will be available this year.

Van Duyn also sees the possibility for the Environmental Protection Agency to reduce refuge requirements.

Under “acid-test conditions,” Bollgard II virtually eliminated boll damage from bollworms, whether treated or untreated, van Duyn says. The treated Bollgard II plots saw less than 1 percent damage over four locations in 2002. The untreated plots saw less than 4 percent damage. One entomologist dubbed 2002 the “Year of the Worm.”

The take-home message is, “Farmers are not going to have be concerned about caterpillar pests,” van Duyn says.

Bollgard is also effective against budworms, beet armyworms, fall armyworms and loopers. In tests in Alabama, researchers, along with Monsanto, suppressed fall armyworm damage tremendously over both conventional and regular Bollgard.

In his tests with colleagues J.R. Bradley, Jack Bacheler, Dan Mott and graduate student Ryan Jackson, van Duyn found very little difference in yields between treated and non-treated Bollgard II.

While the second-generation Bollgard will have the same refuge requirements that growers have been following for the past years, van Duyn would like to see that refuge decline when we get Bollgard II.

A couple of factors influence resistance management, van Duyn says. One is the number of moths that don't come from Bollgard cotton in the environment. The other factor is the number of moths produced out of Bollgard II or Bollgard. “Our refuge is probably not doing much” in the first factor.

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