Native Plants and Neurotoxins

It appears that Native Areas in San Francisco are again linked to toxic herbicides. We’ve posted earlier about Twin Peaks and Garlon/ Roundup.

This time, it’s Imazapyr in Stern Grove.

(posted with permission from A.S.)

Imazapyr is sold under the brand name of “Habitat” when it’s for Native Plant Restoration. Its other trade names are slightly less benign: Chopper. Stalker. Arsenal. Assault.

It persists in the soil for up to 17 months. It’s water-soluble, and moves through soil to get into groundwater.  “Traces of imazapyr were detected in the groundwater even 8 years after application,” according to a  study by scientists from the Swedish University of Agricultural Sciences. (Pest Management Science, June 2004.)

It’s a broad-spectrum killer, so it kills most things it hits (except some weeds that have become resistant). It’s also a difficult herbicide to target with any degree of precision.

In fact, some  plants actually push it out, so it gets into the tangled roots below the soil and kills other plants. From the Nature Conservancy’s Weed Control Methods handbook: “… imazapyr may be actively exuded from the roots of legumes (such as mesquite), likely as a defense mechanism by those plants… the ability of imazapyr to move via intertwined root grafts may therefore adversely affect the surrounding desirable vegetation with little to no control of the target species.”

This is the chemical opponents compared to Agent Orange, when the border patrol planned to spray it on tall cane growing along the Rio Grande river. Communities on both sides feared contamination of the water. The plan was suspended.

In people, it can cause irreversible damage to the eyes, and irritate the skin and mucosa. As early as 1996, the Journal of Pesticide Reform noted that a major breakdown product  is quinolic acid, which is “irritating to eyes, the respiratory system and skin. It is also a neurotoxin, causing nerve lesions and symptoms similar to Huntington’s disease.”

Oh, and Imazapyr is illegal in the European Community.

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