Boulder Creek on the Okanogan National Forest

Case study of a weed management action gone wrong

This web page follows a series of letters to various government agencies as a case study of a noxious weed management action--Boulder Creek on the Okanogan National Forest--and what went wrong with plans. Preferred and recommended actions available to managers were ignored, in preference for more harmful actions, which impacted treated areas beyond acceptable limits.

[Forest Service documentation ignored during the 1999 weed treatment on the Okanogan NF, sent as quotations attached to the February 22, 2000 letter.]

Attachment: Quotes from the SERA regarding off-target plant impacts.

. . .4.2.2. Terrestrial Plants. The primary hazard to non-target terrestrial plants is from unintended direct deposition or spray drift. Unintended direct spray will result in exposure equivalent to the application rate. As discussed in the dose-response assessment for terrestrial plants (section 4.3.3), such exposures are likely to result in adverse effects to a number of plant species.

. . .Direct deposition, either through unintentional direct spraying or spray drift does present a plausible hazard. If plants are accidentally sprayed at the application rates used by the Forest Service, they are likely to be damaged, particularly in the upper ranges of anticipated application rates. This kind of exposure may be regarded as an accidental scenario, which is relatively easy to control with proper management and application. The extent and duration of damage will depend on the time of application and plant species.

. . .(1992), this could damage some sensitive plant species.

. . .Glyphosate can reduce the emergence and weights of progeny seedlings on crops such as corn, soybeans, and johnson grass (Jeffery et al. 1981). It is not clear whether this effect is caused by direct toxic action on the seeds or simply reduced vigor in the parent plant as the seeds develop.

. . .Gross signs of toxicity, which may not be apparent for 2-4 days in annuals or for more than 7 days in perennials, include wilting and yellowing of the vegetation, followed by browning, breakdown of plant tissue, and, ultimately, root decomposition.

. . .In addition to these laboratory bioassays, there are several field studies that have assessed the effects of glyphosate on terrestrial organisms (Appendix 2-2). . . In most cases, the effects noted were changes in population density that reflected changes in food availability or suitable habitat.

. . .Glyphosate residues or perhaps residues of adjuvants used with glyphosate have been shown to affect grazing preference in cattle (Jones and Forbes 1984) but not sheep (Kisseberth et al. 1986).