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The U.S. Environmental Protection Agency is phasing out use of the organophosphate pesticide Guthion (azinphos-methyl) over a number of years to give growers time to learn how to use other, safer pesticides or alternative control methods and gain confidence in them.

Bayer CropScience has voluntarily cancelled registrations of Guthion on all but ten crops.

Use on nursery stock and Brusselsprouts will end on September 30 this year. Use on almonds, pistachios, and walnuts will end on October 30, 2009, and use on the remaining crops—apples, blueberries, cherries, pears, and parsley—will end on September 30, 2012.

The EPA considers Guthion a risk to agricultural workers, water quality, and aquatic species, but not a dietary risk.

During the phaseout, several measures will be taken to mitigate risks, including:

  • A gradual reduction in maximum application rates;
  • Larger buffer zones around water bodies;
  • A gradual elimination of aerial applications to protect water bodies;
  • Buffers around houses and other buildings; and
  • Training of workers who enter areas treated with Guthion to show how to reduce their exposure to pesticides.

    For apples and pears, the maximum application rate will drop to 3 pounds of active ingredient (6 pounds of formulated product) per acre for 2008 and 2009. That will drop to 2 pounds of active ingredient per acre in 2010 and 1.5 pounds per acre in 2011 and 2012.

    For cherries, the maximum rate will be 1.5 pounds of active ingredient per acre in 2008 and 2009, dropping to 0.75 pounds per acre in 2010, 2011, and 2012.

    According to the U.S. Apple Association, apple growers currently apply, on average, 0.78 pounds of active ingredient per application and make 2.4 applications annually for a total of 1.88 pounds of active ingredient per year. In western apple production areas, the average season total is 1.78 pounds per year, and in eastern areas, the average is 2.05 pounds. The figures are from 2006 National Agricultural Statistics Service reports.