Aug 30, 2005
EPA Pulls Plug on Some Guthion Uses

The Environmental Protection Agency has decided to end the use of azinphos-methyl (Guthion, Azinphos-methyl 50WS) on peaches, nectarines, caneberries, cranberries, potatoes, cotton and Southern pine seed.

EPA ruled that existing supplies of the insecticide can be used on these crops through Sept. 30, 2006.

When EPA proposed terminating these so-called group 2″ azinphos-methyl uses, several producer groups asked for an extension. EPA accepted comments this spring, but in its August ruling said it found insufficient reason to justify extending the uses.

Growers with current labeled product can use azinphos-methyl only through next growing season.

The ruling appears in the Aug. 17 Federal Register, at, with a crop-by-crop explanation of why extended use was not granted. For every crop, EPA listed pesticides that it says give effective pest control with less hazard to people and the environment.

Some Background

EPA issued the Interim Reregistration Eligibility Decision (IRED) for azinphos-methyl in October 2001. In May 2002, the technical registrants (Bayer CropScience, Gowan and Makhteshim Chemical Works) agreed to implement the provisions of the IRED by dividing the universe of azinphos-methyl uses into three groups. Group 1 contained 23 crops with little use that were deleted from product labels immediately.

Group 2 consisted of seven uses that were originally scheduled to be phased out in December 2005. It is within this group that uses have now been banned.

Group 3 is comprised of 10 uses that have time-limited registrations pending submission and evaluation of biomonitoring, product efficacy and other data.

For the azinphos-methyl Group 2 crops, EPA received comments and requests to extend some uses, and replied to them in the following manner:


The National Potato Council requested that EPA allow the continued use of azinphos-methyl on potatoes in the Pacific Northwest and expand the use to include Colorado and the Mid-Atlantic region. A request to retain the azinphos-methyl potato use was also received from the Washington State Potato Commission.

The request was based on the need to control the Colorado potato beetle (CPB) and a new pest in the Northwest, the tuber moth. The CPB is an insect with longstanding pest status. EPA said it evaluated CPB in 2001 and found several effective alternative insecticides available. Therefore, the agency focused on the tuber moth for assessing the need for continued use of azinphos-methyl on potatoes.

The pest spectrum has changed since 2001, with the introduction of the potato tuber moth into the Pacific Northwest. However, EPA found that effective controls other than azinphos-methyl, including methamidaphos, methomyl and esfenvalerate, are available. Further, usage data indicate that use of azinphos-methyl on potatoes in recent years has been minimal, EPA said.

Read the full notice on the Federal Register at

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