Of the 3,000 native species of plants in Colorado, 500, or 17 percent, have already been displaced by noxious weeds, states the seventh edition, which is published by the Colorado Weed Management Association.
Invasive weeds are plants that are not native to an area which, because they do not have natural predators and enemies such as insects or diseases, grow unchecked, displacing the native plants.
Controlling weeds in San Miguel County is the province of Sheila Grother, the county's weed control officer. On this late August afternoon Grother, along with two weed control assistants, Marla Anderson and Milton Spor, and Greenbucks coordinator Leigh Sullivan are leading a weed identification walk and pull in Ophir.
"By the time we are finished here we will have prevented millions of seeds from dispersing and taking root," said Grother.
The walk begins just yards from the Ophir Town Hall in an open meadow that is sprinkled with yellow toadflax, a non native commonly known as butter and eggs. The yellow flowered plant resembles the snapdragon and was introduced from Europe as an ornamental plant. Without natural predators in the United States, it has become a serious problem in rangelands and mountain meadows. The plant, a perennial, reproduces from seed, as well as from underground root stalks.
The group fans out into the meadow, pulling up the toadflax, one plant at a time. Some plants come out easily and some come with their horizontal root balls still attached. A quick look at the ground and you can see where there are still roots in the ground.
At least we have prevented the dispersal of more seeds, Grother reminds the pullers when the job begins to feel a bit overwhelming. There are only five of us, and in the short time we can make only a small mark on this field.
"This is an example of the problem that arises when people say we shouldn't spray," said Grother. In spite of Greenbucks' weed pulling days and in spite of the time that Grother and her crew (this is the first summer she has had hired help) put into pulling weeds and educating others on which weeds to pull, there just are not enough hands to pull out all the weeds that are invading the county. And in particular, with a weed like toadflax that reproduces by root growth, roots inevitably left in the ground return and grow the following spring.
"This is a creeper. The root hairs are capable of regenerating," Grother explained.
Toadflax, which has been limited to the upper basins of the San Miguel, where it was introduced as an ornamental, was first seen in Norwood this summer, Anderson pointed out.
"When we saw it in Norwood, Sheila hit the skids and we sprayed it. It had come down the Gurley Ditch," she said.
Ornamentals, like toadflax and oxeye daisy – another non-native that has escaped the bounds of the gardens in the Telluride region where it was planted and spread aggressively into meadows and fields – might begin in the high basins of Telluride and end up in the lower sections of the river. The resilient seeds are easily carried down stream by tributaries and the main stem of the San Miguel River, Grother said.
On the edge of the meadow Grother spots a scentless chamomile plant. Scentless chamomile, also an escaped ornamental, has a small white daisy flower with feathery leaves. The plant is illegal to plant or cultivate in San Miguel County and landowners are required to remove it from their property. It has no forage value for wildlife and can blister muzzles, irritate mucous membranes, and cause skin rashes on livestock. Also imported from Europe, the plant has become well-established in Vail and Silverthorne and Grother is determined to keep it from establishing a foothold in the San Miguel County. This is the 30th location in the county where it has been found.
"We have an opportunity to stop this one before it becomes like oxeye daisy and toadflax," she said.
Having found one plant, Grother knows there are likely many somewhere else. She looks around and spots a group of plants across the street. The toadflax will have to wait for another day, and Grother directs her cobbled-together weed crew to pull all of the scentless chamomile. We turn on the plant and within 20 minutes the white daisies have been pulled and stuffed into heavy duty plastic bags Grother has brought along. To keep the plant out, the landowner will have to pull plants for several years, as it reproduces by dispersing thousands of seeds.
"If we had left this alone, a year from now this patch would have three times as many plants," said Grother. "Five years from now this entire area might look like Silverthorne."
The pulled weeds are composted – "You should see the pile I have. We have it coming in by the truckload," Grother said – which destroys most of the seeds, and then the composted material is burned in a weed incinerator.
"It is the only one of its kind in the world," said Grother, who designed the machine and sent plans for it to the experts at Mountain Village Metro services for construction.
She will call the landowner to advise them of the scentless chamomile. "Better than leaving a note on the door where I can only explain so much," she said.
Below the now-bagged scentless chamomile is a large patch of oxeye daisies, one more ornamental, planted by well-intentioned gardeners, and which has now escaped the bounds of those gardens.
Oxeye daisies tend to be a monoculture, said Grother, elbowing out native plants and taking over their space and water. The ever-aggressive oxeye, like toadflax, is now spreading to more fragile high mountain meadows. Wildlife do not eat it and it invades and takes over riparian areas.
That this patch of oxeye is in a ditch that drains into the Howard's Fork has serious implications for downstream landscapes, Grother said. Carried downstream by water, the seeds travel long distances, from the Howards Fork to the South Fork of the San Miguel to the mainstem of the river and down.
While Grother, her crew, and the volunteers they can pick up along the way spend much time during the summer pulling and bagging weeds, Grother depends on volunteer help throughout the county to keep track of where weeds are sprouting up. People call her with tips, they bring samples to her, and they send digital images via email. Most importantly, they help her pull the weeds.
"The more the merrier," Grother said gleefully.
Tuesday next week Grother is leading a weed tour through gardens in the Town of Telluride. In addition to pointing out invasive ornamentals, she will be showing participants good plants, ones that tolerate drought, look nice and which do not escape domestic gardens to spread through neighboring wildlands.
The tour begins 10 a.m. at Town Park. Grother will talk about good and bad plants and then lead participants on a tour of town, including the town's River Trail, to look at what works and what does not work. Wear good shoes, apply sunscreen and bring gloves, if you have them. After the talk, tour and lunch, Leigh Sullivan will lead a weed pull. Participants who tour and pull for four hours earn a Greenbuck.