Invasive Weed Strategies

Narrow-leaf hawksbeard, a new invasive weed in northeastern Montana has become an increasing problem for area farmers and ranchers. Though technically a winter annual the weed has the ability to germinate whenever conditions are favorable, and can have several generations per year. It is extremely cold hardy and a prolific seed producer. It infests crops, rangeland, CRP, pastures, hay meadows and roadsides and waste areas. It has spread through six Montana Counties and into North Dakota. It is the Weed of the Year for North Dakota in 2018.

Research by Ed Davis MSU Weed Specialist, Brian Jenks NDSU Weed Specialist, Jane Mangold Extension Rangeland Weed Specialist and Shelley Mills over the last four years has provided growers with options to manage this weed when little was known about it. Shelley has presented the research findings to groups of producers and agronomists 18 times in the last two years across northeastern Montana and as far away as Boise, Idaho. In a recent survey of 48 participants of the workshops, 92 percent had incorporated some management strategy learned through Extension programming. Area agronomists attending the workshop noticed an 82 percent increase in hawksbeard inquiries from producers looking to manage weeds over the last two years.

Over 80 percent of the attendees added fall applications, spring and fall applications and selected herbicides based on their ability to manage hawksbeard after learning that these strategies can help to minimize the impact of the weed. Other approaches included applying herbicides earlier in the spring and later in the fall, changing the rate of glyphosate products used in burn-down operations, rotating crops and tillage. Producers also felt more confident in their identification and herbicide selection when managing hawksbeard following the workshops. Currently hawksbeard is being managed on 109,350 acres of the 189,900 acres of crop land owned or managed by 48 respondents, with roughly another 30,000 acres at high risk of infestation. Without the management techniques taught by Extension, growers estimated an average loss of $63 per acre which represents a total of $6,127,000 in potential lost revenue to hawksbeard.

For more information about narrow-leaf hawksbeard management please contact your local MSU Extension office or contact Shelley Mills at 406-228-6241.