MSU Extension Service Resource For Weed Watch - weeds, pesticide, control of weeds, weed pictures and Related Links

  • MSU Invasive Rangeland Weed Extension
  • Toxic Plant Database
  • 2006-2007 Weed Management Handbook
  • 1994-1995 Commercial Horticulture Weed Control Handbook
  • Western Rangeland Weeds Resource
  • A Plant by Any Other Name - Another new web page provides access to a specialized segment of the GRIN database devoted to information on noxious weeds. Both taxonomy web pages are part of the GRIN database, which includes over 62,000 botanical names of mainly economic plants.
  • Montana Knapweeds: Identification, Biology, and Management
  • Biology, Ecology and Management of Montana Knapweeds
  • Leafy Spurge: Biology, Ecology and Management
  • Whitetop (Hoary Cress)
  • 10 steps to improve weed management
  • Rehabilitation of Weed-Infested Rangeland
  • Pacific Northwest Weed Management Handbook
  • MSU weed experts recommend fall herbicide application in riparian areas
  • Licking Houndstongue
  • Noxious Weed Alert: New Yellow Starthistle Reports
  • Free Web book shows maps are key to battling noxious weeds

    Noxious weeds are like a wildfire…sometimes simmering slowly across a landscape, other times exploding with fury. But no matter the timeline or method, destruction is certain: Noxious weeds choke out native plants, reducing habitat for wildlife and livestock and spoiling landscapes for hunters and hikers along with farmers and ranchers.

    Like firefighters, those who battle noxious weeds must map their war zones.

    By mapping weed infestations, land managers can track the total acreage under siege and determine how quickly infestations are spreading. Weed surveys also help pinpoint outbreaks of new weeds entering Montana from neighboring states.

    A Montana State University Extension Service publication by Diana Cooksey and Roger Sheley outlines the methods for mapping noxious weeds, from hand-drawing to GPS systems. Cooksey, land resources project coordinator, and Sheley, MSU Extension's noxious weed specialist, describe which maps, drawing instruments, symbols and codes to use, and tell how to record, submit and interpret data.

    More details, Visit:

  • Pesticide Drift
  • Pesticide Reference Materials
  • Pesticide Interactions and Compatibility and Read the Label of Four Types of Interactions
  • Water Effects On Pesticide Performance
  • Montana Private Pesticide Certification Manual
  • Weed control under drought conditions
  • Managing Weeds After Wildfire
  • Oxeye Daisy
  • How to Make Biocontrol Work Against Leafy Spurge
  • Common Tansy Is No Pansy

    Common tansy (Tancetum vulgare), also known as golden buttons and garden tansy, is a perennial herb in the sunflower family. The plant readily invades roadsides, fence rows, pastures, stream banks, and waste areas throughout North America. While it is not a statewide noxious weed, it has been declared noxious in Broadwater, Beaverhead, Gallatin, Silverbow, Meagher, and Carbon counties.

    Mature common tansy plants are easily recognized by the flat-topped clusters of small, button-like, yellow flowers they bear in the summer. Stems grow in large clusters up to 6 feet high and are mostly hairless, often purplish-red in color, and extensively branched towards the top. Leaves are finely divided into leaflets giving the plant a fern-like appearance. Common tansy has a strong odor when crushed. Common tansy, native to Europe, has a long history of medicinal use. It was first introduced to North America for use in folk remedies and as an ornamental plants. Use of common tansy led the governor of Massachusetts to list common tansy as a necessary plant for colonial herb gardens in the 1600s. This led to widespread cultivation of the plant and its inevitable escape into fields and roadsides. By the 1800s this weed was growing wild throughout the Northeast. In 1912, it was reported as far west as Kansas and it was widespread in California by 1952. Limited research on control of common tansy has been conducted. As with most weeds, prevention of the establishment and spread of infestations is the most cost-effective management tool. The most effective herbicide for common tansy control is metsulfuron (Escort). In herbicide trials in northern Idaho, metsulfuron applied at 0.3 oz/acre yielded 99% control after three months and 98% control 15 months after treatment. Metsulfuron should always be used with a high quality, nonionic surfactant to ensure penetration of the herbicide into plant tissues. Picloram (Tordon) also provides good, short term control of common tansy.

    Neither of these herbicides should be used to control common tansy infestations near water as these chemicals are persistent in soil, and have potential to leach into groundwater. Accordingly, metsulfuron and picloram should not be used on any site where the depth to water table is less than 20 feet. This limits the usefulness of these chemicals for control of common tansy because the plants often grow near waterways. Glyphosate (Rodeo) and 2,4-D amine are alternative herbicides for use near water, but they are not very effective for controlling common tansy. Mowing provides an alternative to herbicide use near waterways, and has been reported to marginally control common tansy.

    Common tansy contains alkaloids that are toxic to both humans and livestock if consumed in large quantities. Cases of livestock poisoning are rare, though, as tansy is unpalatable to grazing animals.

  • Pesticide Labels


Pesticide Safety Education Program

Montana State University
P.O. Box 172900
Bozeman, MT 59717-2900
Tel: (406) 994-5067
MSU Pesticide Safety Education Program: