A representative of Dow Chemical is set to attend a meeting in Durango from 3 p.m. to 4:30 p.m. today at the Pine Room at the La Plata County Fairgrounds to discuss the effects of a Dow herbicide on good crops as well as bad weeds.

Deborah Morton will meet with agriculture officials and commercial and backyard farmers who tentatively call themselves the Herbicide Carryover Working Group.

The name is apropos because the chemical herbicide in question doesn’t decompose. It kills broadleaf bad guys such as Canada thistle and members of the knapweed family. But it also kills broadleaf peppers, spinach and tomatoes that are grown in compost containing manure from livestock that forages on fields treated with the chemical.

The best known of three classifications of killer chemicals is Milestone, which was registered by Dow in the United States in 2005.

Complaints about aborted growth among the popular broadleaf crops found in home gardens and the fields of commercial growers piled up over the years.

Darrin Parmenter, the Colorado State University Cooperative Extension horticulturist in Durango, would receive a couple hundred complaints annually about broadleaf crops that never germinated or shriveled early.

Over four or five years, investigation concluded that herbicides, not a virus or an insect, were responsible for the broadleaf dieoff.

Dow Chemical is open about the effects of its herbicides.

A Dow AgroSciences website alerts Milestone users about its characteristics. The chemical doesn’t degrade in plants. It takes three days to pass through a grazing animal’s digestive system, and the animal’s manure may contain enough aminopyralid to injure broadleaf plants, including ornamentals.

daler@durangoherald.com