by Dennis Cash and Tonda Moon, MSU Animal & Range Sciences Extension Specialists and Montana Department of Agriculture, respectively.


The spread of noxious or non-native weeds causes millions of dollars in economic losses every year. In the West, invasive weeds reduce forage production on grasslands, which limits the usable habitat for wildlife and livestock. Weed control is often cost - prohibitive on fragile grasslands where access is limited, or the resource is already of marginal value to justify control. For these reasons, prevention of weed infestations is the most practical, inexpensive methods of weed control. In Montana, approximately 7 million acres of rangelands are infested by 32 alien weed species. The most serious of these weeds is spotted knapweed, which affects 4.5 million acres.

Invasive weeds have been introduced by a variety of factors, such as the importation of infested grains or seeds in the late 1800’s. Secondary weed invasions occurred by the movement of wildlife, livestock or hay, plus transportation and waterways. Many state and federal agencies are involved with prevention efforts to exclude initial infestations of new weeds, as well limiting the secondary spread of all invasive weeds. In Montana, weed control programs are active in every county and on tribal reservations. Weed awareness and prevention programs have focused on travel into backcountry areas for purposes such as recreation, grazing and logging.

A major component of invasive weed prevention is the Montana Noxious Weed Seed Free Forage (MNWSFF) Program. This effort was initiated in 1972 as a voluntary program in Gallatin and Lewis & Clark counties to provide weed-free hay for backcountry horse travel. By the late 1990’s, the MNWSFF program had expanded to most Montana counties. Currently, most Federal and State lands are now under “exclosure” orders – all hay, feeds and mulches for road projects must be “certified” as weed seed-free. Hunters and recreationists who routinely travel with horses in Montana’s backcountry areas have quickly adopted the MNWSFF effort. Weed seed free hay, grain or pellets are commonly packed for feed, and this restricts new weed invasions on thousands of acres each year. The Montana Department of Agriculture coordinates a certification program for weed seed free forages, and a list of hay growers is available every fall. The major components of MNWSFF certification is a field inspection prior to harvest to assure that no noxious weeds are present, and a tagging system for verification.