What is that growing again this year along our highways, streets and roads, in our parks, forests and home landscapes? Sadly, the correct answer is “invasive weeds.”
Cheatgrass seeds arrived in the U.S. from Eurasia centuries ago and in Flagstaff in the early 1900s. Many more species were accidentally or intentionally introduced, and they’re still thriving in private and public landscapes and providing fuel to wildfires. Museum of Northern Arizona’s herbarium collection has specimens of invasive weeds, including Common mullein, Cheatgrass, Field bindweed and Foxtail barley grass, dating back as early as 1915.
Invasive weeds steal water and nutrients from native species, out-compete natives by blocking out the sun’s rays, and reduce biodiversity. They crowd out natives, establishing mono-cultures which spread aggressively. Complete native ecosystems have been destroyed. Tamarisk has taken over riverbanks, altering the soil chemistry making it difficult for natives to survive, and because tamarisk is more flammable than native willows or cottonwoods, it introduces wildfires to riparian areas that are not adapted to fire.
The public’s fight against invasive weeds has a long and productive history in Flagstaff. When I first arrived here in 2004, I saw a specimen of Dalmatian toadflax and a hand-written note hanging on a sign at Buffalo Park encouraging walkers to pull it. Since then, longtime residents have told me the population of Dalmatian toadflax is now substantially reduced. I’ve seen lots of evidence of passing weed warriors along FUTS and forest trails. One woman I recently met adopted 2 miles along Townsend-Winona Road and pulls invasives every year! That’s dedication.
It’s important to note that there are native species that can be confused with non-native species, so if you’re not sure, check twice before you pull. For example, native purple-flowered Wheeler thistle and red-flowered Arizona thistle have smooth, round stems. Non-native thistle stems usually have nasty spiny-wings, which can inflict seriously painful damage to the skin.
A docent at The Arboretum at Flagstaff has good advice for anyone who wants to eradicate invasives. He said, “Get ’em while they’re young and easier to pull.” Following this advice, 19 volunteers for Grand Canyon Trust, AZ Native Plant Society, Museum of Northern Arizona and Master Gardener’s recently participated in a weed pull at Pioneer Museum to remove young Diffuse knapweed rosettes. This is our third year at this location, and results have been astounding. Not that we’re done, of course! Work will continue for years because more seeds are waiting in the soil to germinate. However, control will require fewer and fewer workdays. We have already seen increased populations of beautiful native Scarlet gilia, Penstemon and Geraniums. Success!
If you would like to participate in a weed pull along Fort Valley Road today or on June 9, or volunteer for the Vegetation Program at Grand Canyon or for other Grand Canyon Trust projects, visit to their website at www.gcvolunteers.org. You’ll be glad you did.
Master Gardener Association’s blog at coconinomgassociation@blogspot.com frequently announces upcoming volunteer activities also.
Dedicated volunteers have spent years in collaboration with the city removing Scotch thistle from Picture Canyon and restoring its wetlands. www.friendsoftheriodeflag.org has information on this and other volunteer Rio projects.
For years, another group has pulled Scotch and Bull thistles at Logan’s Crossing, a well-loved area for bird watchers. Contact WeedWarrior1@live.com to participate.
One way to keep those invasive weeds out of the landscape is to plant more native species. What fun this can be! With this goal in mind, on June 11 through 13 and Aug. 6 through 8, AZ Native Plant Society will offer two non-credit native plant workshops. Each will include information on identifying native plants and invasive weeds, controlling weeds and landscaping with natives. There will be field trips to practice our identification skills and to visit local gardens. Registration is through Coconino Community College at 526-7654. Class size is limited to 10.
You will find helpful information on identification and control of many common high-elevation invasive weeds at http://extension.arizon.edu/coconino-master-gardener-2012-home-and-garden-show-powerpoints.
English author John Heywood said, “Many hands make light work.” That’s true when it comes to weeds. Please consider becoming a “Weed Wizard” and make those weeds disappear!
Dorothy Lamm, a Master Gardener, is a member and a volunteer at the Native Plant Society and the Grand Canyon Trust. Her email address is lammdory@gmail.com. Dana Prom Smith edits Gardening Etcetera. His email address is stpauls@npgcable.com. His blog is http://highcountrygardener.blogspot.com.
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