Amitraz

The ag industry is stressing to growers the importance of refugia to preserve this valuable technology.

EFFORTS to control insects while fighting resistance is "a race against time and genetics," according to Monsanto. Nowhere is this more true than with Bacillus thuringiensis (Bt) crops, especially Bt cotton. Dr. Ron Smith, entomologist for Auburn University, credits Bollgard technology as having "literally saved the cotton industry in Alabama and in other areas that historically favor high budworm pressure, such as the hill areas of Mississippi and regions in Louisiana, south Georgia, and the Florida Panhandle."

Fielding Cotton Concerns

Smith told Monsanto cotton losses in Alabama were 50% to 80% from tobacco budworm in the two years before the introduction of Bollgard cotton. But the lighter pressure associated with Bollgard use has caused some growers to forget what it was like pre-Bollgard.

But despite mounting concern about losing the technology, farmer compliance to Bollgard cotton refuge requirements slipped at least 10% during the 1998 growing season, according to Monsanto's refuge monitoring program. Some university entomologists think that compliance may have been even lower, closer to between 80% to 85%.

Because of "willful non-compliance to refuge requirements" stated in the Monsanto technology agreement for Bollgard use, some growers will even lose their technology license this year.

In 1997, entomologists estimate Bollgard compliance was at about 95%, almost a 5% drop from the nearly 100% compliance in 1996, when Bt seed was first introduced to the commercial market.

This disturbs many in the industry, especially since they say there is sound scientific thinking behind the refuge requirements - lepidopteran cotton pests have shown an ability to develop resistance to a variety of chemical insecticides. The refuge assures that some lepidopteran populations are not exposed to the Bacillus thuringiensis var. kurstaki (Btk) protein so when the pest mates, it retains it susceptibility gene and passes that gene on to the offspring.

Making A Refuge Work

Here are the two widely accepted options for a refuge:

Growers must plant 25 acres of cotton without the Bollgard gene for every 100 acres of Bollgard cotton planted. The 25 acres without the transgenic gene may be treated with insecticides that control tobacco budworm, cotton bollworm, and pink bollworm - with one exception: you cannot use foliar Btk insecticide products on these 25 acres.

Growers may plant 4 acres of cotton without the Bollgard gene for every 100 acres of Bollgard planted. These 4 acres cannot be treated with amitraz, endosulfan, methomyl, profenofos, sulprofos, pyrethoids, emamectin benzoate, tebufenozide, indoxacarb, Helicoverapa zea nuclear polyhedrosis virus, chlorfenapyr, spinosyn A + spinosyn B, thiodicarb, pepper spray, garlic spray and/or foliar Btk insecticides, as well as any other products specifically intended for control of tobacco budworm, cotton bollworm, and pink bollworm.

However, acephate or methyl parathion may be used as long as it's a single application of not more than .5 pound of the active ingredient per acre are used.

These refuge requirements need to be adhered to grower-bygrower, farm-to-farm, Monsanto says - without the mindset that growers can depend on the farmer next door or down the road to plant a refuge and have that count as his or her own.

Although the majority of farmers have complied with refuge requirements, when faced with what's at stake, non-compliant farmers are realizing that insect resistance is everyone's problem.

If refuge requirements are not followed, it's back to square one planting non-Bt cotton the traditional way and battling the bollworm and tobacco budworm for the entire season.

Copyright Meister Publishing Company Mar 1999
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