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Arizonans control aflatoxin

Arizona cotton growers have aflatoxin on the run, and they are hoping they can soon send the pink bollworm (PBW) chasing after the fungi out of town.

Wiley Murphy, Marana, Ariz., cotton producer and chairman of the Arizona Cotton Growers Association pink bollworm committee, told the association's annual meeting that there are funds to initiate a pink bollworm eradication program in President Bush's 2006 budget.

Arizona growers overwhelming approved an eradication program last summer and agreed to fund it at $7 million. However, they need federal help as well and no funds are available this season so the effort will not start until at least 2006.

“That is the bad news,” Murphy told ACGA's annual meeting recently in Casa Grande, Ariz.,

The “good news” is that a PBW eradication program in the Trans Pecos region of West Texas, New Mexico and northern Mexico is moving into its fourth year with massive drops of sterile pink bollworm moths scheduled this season to hopefully begin the final phase leading to PBW eradication in that area. With that accomplished, when the Arizona program begins the threat of infestation from those areas will be all but eliminated.

Using Bt cotton, pheromone confusion techniques and pesticide sprays, growers in that region have reduced PBW numbers to levels low enough to begin sterile moth drops.

PBW larvae are raised and sterilized in a lab in Phoenix owned by California cotton growers for use in the long successful pink bollworm exclusion program in San Joaquin Valley cotton. Larvae are dropped by planes to breed with any fertile, native moths which will not produce offspring. This technique has been used successfully for almost 40 years to keep PBW out of the San Joaquin Valley.

Currently the lab is producing 2 to 2.5 million sterile larvae per day, but it is capable of producing 10 times that amount.

Clyde Sharp of Roll, Ariz., ACGA president, said limited sterile moth drops last season in isolated areas of the Texas-New Mexico-Mexico eradication zone resulted in almost 100 percent eradication.

AF 36 successful

More than 20,000 acres of cotton in Arizona and 5,000 acres in Texas were treated with Aspergillus flavus strain AF36 last year to reduce aflatoxin in cottonseed, reported Larry Antilla, director of the Arizona Cotton Research and Protection Council (ACRPC), which won EPA registration to produce and market AF36.

AF36 was discovered by Dr Peter Cotty, research plant pathologist, at the Southern Regional Research Center in New Orleans. When wheat inoculated with the non-aflatoxin-producing-mold and spread underneath the cotton canopy, the undesirable aflatoxin-producing mold is suppressed and/or displaced.

Reducing aflatoxin in cottonseed is important to desert cotton growers because cottonseed with more than 20 parts per billion aflatoxin cannot be fed to dairy animals. Cotton producers in Arizona and South Texas are discounted for up to $25 to $30 per ton below market on their whole cottonseed sales.

More than 100,000 acres of Arizona cotton is affected by aflatoxin each year ad as much as 500,000 acres of South Texas cotton suffers from the same malady.

Antilla told the ACGA membership that early data from AF 36 applications in Arizona reduced aflatoxin by more than 80 percent in 2004. Plus, monitoring is confirming that there is a carryover control from year to year where AF36 was applied.

“There is no doubt the technology is working,” Antilla said. “What we need now is for more growers to use AF36. We have made great strides in the production of AF36, and we have product available.”

Some of that product went to South Texas last season and was used to successfully reduce aflatoxin there in cotton. Cotty said Texas growers rotate cotton with corn, and hopefully AF 36 will reduce aflatoxin in corn as well.

Antilla said growers in the desert cotton growing areas of Southern California want to try AF 36 this season California pistachio growers also want to test it on their tree nut crop. It may also have application in peanuts, walnuts and almonds where aflatoxin can be a problem.

It costs about $5 per acre to apply AF36 with a potential return of five to six times that based on the discount for aflatoxin contaminated cottonseed.

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