A conifer tree-killing herbicide would have been banned from Oregon roadsides this month, but the rule has been delayed by a request from chemical giant, Bayer AG.

Perhaps best known for aspirin, Bayer also makes agricultural products like Perspective, an herbicide once commonly used to control weeds and reduce fire risk along highways. The active ingredient, ACP, is behind killing about 2,100 ponderosa pines in Deschutes National Forest near Sisters, Oregon.

The product label says not to apply it near “desirable” roots— a warning that came after a wave of tree deaths were linked to ACP in 2011. But as one product made by DuPont was pulled off the market, Bayer launched a different brand. 

That’s the stuff state contractors working for the Oregon Department of Transportation sprayed outside of Sisters until 2015. Last year, complaints about dead and dying trees led the Oregon Department of Agriculture to launch an investigation and order a temporary stop to ACP applications on road sides and rights of way.

Along the Highway 20 site, it found 18 of 22 foliage samples from those trees tested positive for ACP, three years after the last application. The agency got more than 3,000 comments as it decided to move forward with a permanent ban on spraying certain areas and milling exposed wood.

A week before that rule would have taken effect, Bayer appealed for more time to dispute any state restrictions on its product, which is federally approved by the Environmental Protection Agency for use on rights of way.

An executive with Bayer’s Environmental Science Division sent a letter to ODA on March 20, saying it plans to show there’s no need for more regulation, and if that fails, advocate for “a more tailored rule,” one that the company states would “manag[e] the risk of herbicide exposure to desirable trees without unfairly singling out one product line for unjustified and unequal restrictions.”

Bayer asked for a three month extension, the maximum permitted by state law. ODA responded by offering the minimum: 21 days.