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EPA Revokes Registration of Aminocyclopyrachlor (Imprelis)

By
  • Chris English
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On August 11th, 2011 the herbicide Aminocyclopyrachlor, licensed by Dupont as Imprelis, was banned from sale, use and distribution by the EPA. One week prior to the announcement Dupont voluntarily began a recall program after numerous reports of tree losses following application of the herbicide. Registered on September 2nd, 2010 the product was on the market for less than a year before significant damage to spruce and pine trees had occurred. The majority of the early applications were done professionally on commercial properties; however, residential sale was planned for later this year under the trade name MAT28. 

Imprelis is considered a synthetic auxin and while auxins are critical to plant metabolism, high concentrations produces excess ethylene and inhibits growth. The most commonly used auxin for weed control is 2,4-D (2,4-dichlorophenoxy acid). Dupont and EPA warn not to use grass clippings from treated areas for mulching or compost. Grass clippings must be left in place or disposed of in the trash. 

Current EPA methods that may work for analyzing  this compound are EPA 8151A in a waste situation or EPA 515.4 Rev 1.0 (2000) for drinking water. Both methods involve derivitization prior to GC/ECD analysis. We recommend using the Rtx-CLpesticides and Rtx-CLPesticides2 for these dual column methods. Let us know if you have analyzed Imprelis or need assistance.

Special thanks to Al Sensue, Sr. Technical Service Representitive, for his contributions to this article.

Notes: Aminocyclopyrachlor cas#858956-08-8. The esterified compound, aminocyclopyrachlor-methyl cas# 858954-83-3.

This PSU website has some great pictures:

http://blog.pested.psu.edu/2011/08/08/imprelis-update/

Comments

Thu, Sep 29, 2011

We (North Coast Labs, CA) might interested in analyzing for aminocyclopyrachlor in environmental samples (waters, soils, plants etc.). We would need some referance standard (I don't see any commercial standard vendors selling it yet, but dupont should supply some if we ask). I could develope a method if dupont can't share theirs. We already routinely analyze for several related herbicides like aminopyralid, clopyralid and imazapyr. I'm very interested in these pyridine carboxylic acid herbicides lately (Niacin analogues). I would probably be doing it by LCMSMS and thus could expect confirmable detection limits as low as .1ppb in water and perhaps 1ppb in soils (possibly lower). I read about this stuff first in Mother Earth News recently- it's really making a splash (actually I first heard about aminopyralid and it's "killer compost" the same way, which prompted me to get that analysis going). Bradley Thompson

[...] the surrounding trees resulting in Dupont pulling the product.  You may remember that Chris English blogged about this topic when the EPA first revoked the [...]