Collaboration and Outreach Creates Successful Invasive Plant Program

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Larimer County in Colorado is typical of counties along the front range of the Rocky Mountains. Public lands comprise over 50% of the county, most of which lie within Roosevelt National Forest and Rocky Mountain National Park. Elevations range from about 4,800 feet in river valleys to almost 14,000 feet on mountain peaks.

Added to this geography is a rapidly growing population of about 300,000 residents who are concerned for the environment, but may lack knowledge about natural resource management. Mix in infestations of the knapweeds (Centaurea spp.) such as spotted and diffuse, leafy spurge (Euphorbia esula), Dalmatian toadflax (Linaria dalmatica, L. genistifolia), and Canada thistle (Cirsium arvense) along with nine other priority weeds, and management becomes challenging. Add newly invading species such as yellow starthistle (Centaurea solstitialis), purple loosestrife (Lythrum salicaria), and Mediterranean sage (Salvia aethiopis) that are targeted for eradication, and Tim D’Amato’s days become pretty lengthy.

D’Amato has managed the Larimer County Noxious Weed Control Program based in Fort Collins, Colorado for the past three years. Prior to accepting his current position, D’Amato worked for more than 16 years as a research associate in the weed science research programs of Drs. Ed Schweitzer and Phil Westra at Colorado State University.

“Larimer County is one of the largest counties in the state encompassing 2,640 square miles that include some of the finest irrigated farmland in the state as well as vast stretches of scenic ranch lands, forests, and high mountain peaks,” says D’Amato. “The southeastern corner is populated by the growing cities of Fort Collins and Loveland, but there are still a lot of open rangeland and wildland areas where noxious weeds can establish and thrive. Larimer County also serves as a gateway to Rocky Mountain National Park with about 3 million visitors a year, so it’s important we do our part to protect the Park from invasive plants.”

A powerful tool used by D’Amato to build local and state-wide support for his program was to develop a partnership with weed scientists at Colorado State University (CSU). “We are very fortunate to have CSU in our county and can use their expertise and guidance to develop the most accurate management recommendations for invasive plants,” says D’Amato. Weed Scientists at CSU share D’Amato’s enthusiasm for the collaborative effort. “Tim has a unique professional background that provides him with special insights into long-term weed management strategies required for successful weed management. He is one of the most talented, hard working, creative, and people-oriented people ever to work in my program,” says Westra. “Tim always looks to discover and use new weed management tools that will benefit land managers in their efforts to control noxious weeds. His leadership on locating research sites and setting up well conducted field research continues to be a great asset to the weed science program at Colorado State University.”

Larimer County Weed District has cooperative projects on biological control of invasive plants, herbicide field trials and research on degraded site rehabilitation. With reduced funding for some university and county extension activities, the weed district has filled the void by providing literature and field tours for land managers. “Land owners and managers really enjoy tours of our research and demonstration areas, where they can compare side-by-side treatments on invasive plants,” says D’Amato. It also allows D’Amato, his staff, and research partners to stay updated on current technology for managing invasive plants.

Canada thistle is one of the most pervasive weeds in Larimer County, and field trials conducted in cooperation with CSU showed that Milestone® herbicide provided excellent control of the weed. The weed district applies Milestone at the labeled rate of 7 fl oz/acre to control Canada thistle and has achieved excellent control. “Milestone is a good choice for a lot of land managers in our county and they are happy with the results. We have found that we are getting better and more consistent, long term control of Canada thistle compared to treatments we made in the past with dicamba and 2,4-D,” says D’Amato. “We are also working on demonstration and research projects to restore degraded sites once invasive plants such as knapweeds and Canada thistle are controlled. Restoring a desirable plant community on degraded lands is a real challenge, but important to stop reinvasion of noxious weeds.”

The highest weed management priority in the county is newly invading noxious weeds. The Larimer County Noxious Weed Management Plan requires eradication of all “List A” species—weeds that are not well established in the state. The county receives federal funding through the Interstate Pest Control Compact (IPCC) to support two seasonal employees for six months. These seasonal employees spend half of their time controlling yellow starthistle and half their time controlling other List A species. “We refer to this as our A Team since they target new invaders,” explains D’Amato. The seasonal employees are trained and licensed to apply herbicides and spend the summer controlling invasive plants. Most of the control work is with backpack sprayers or physical removal of small infestations. “The majority of infestations are on private lands and we’ve had a positive response and support from private landowners for this program.” There is no charge to landowners for controlling A-Listed weeds.

When they aren’t treating weeds, the A Team is working with the public on outreach and education on invasive plants. Crews also monitor high risk areas for invasion such as recreational trailheads and other access sites. “There was a yellow starthistle plant found at a trailhead to Rocky Mountain National Park a few years ago. Luckily it was found and removed before producing seed,” says D’Amato.

D’Amato’s personal contacts with key landowners, agency leaders, Cooperative Extension, and regional noxious weed researchers helps glue together unique research and outreach partnerships in Colorado. “Tim is able to bring together people of diverse weed management philosophies in a way that creates collaboration rather than division.  Tim’s warm people management style ensures that the Larimer County A Team actually functions as a team and is highly effective in the ongoing process of weed management in Larimer County,” says Westra.

“Our goal in Larimer County is to educate and engage as many people as possible to help prevent introduction and spread of invasive plants in the county,” says D’Amato. “The emphasis in our county is to support research, education and outreach rather than enforcement and I believe it is paying big dividends in our program. We still have weeds, but by engaging the public and using science-based results to select the best control option we are containing our larger infestations and stopping newly invading weeds.”

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Published 2011; trademark updated June 2019.