Montana hay growers and others should work together to control whitetop, a noxious perennial weed posing an increasing threat to the state’s hay supply, says Tom Benson, coordinator for the Lake County Weed District.

Whitetop, says Benson, “will displace your desirable vegetation, whether it’s alfalfa, whether it’s grasses – it really doesn’t make a difference.”

Part of what makes the weed so hard to control is the ease with which infestations spread, he says. Because whitetop matures early, its seeds are unintentionally baled and fed to livestock in first-cut hay, then spread through manure. “A mature plant will produce up to 3,000 seeds per year. Once it goes to seed that first year, it’s a long-term battle.

“We probably only have a seven- to 10-day window left in the spring to control whitetop before the majority of the population has set seed. Spraying is still effective now on the mature plant, but the seeds will still be viable” and can become somewhat resistant to future herbicide treatments.

A second treatment after fall rains have begun and plants start to green up is advised. Effective grass and rangeland herbicide options include 2,4-D Amine, Telar, Escort, Cimarron Extra and Chaparral; for alfalfa, Velpar may be the only option, Benson says.

Increased vigilance; immediate removal of new plants and careful grazing, cropping and irrigation management can curb the plant’s spread. But the greatest hope in checking the noxious weed will have to come not only from private landowners but also from state and local governments and the Confederated Salish and Kootenai Tribes, he warns.

“We operate under the Montana Noxious Weed Law and the Lake County Noxious Weed Law, while the tribe sets their own weed-management plan.” Controlling the weed will require getting “everyone on the same page as far as what we are going to do to get this under control.”