A wet spring and summer has given rise to hillsides covered with infestations of oxeye daisies, a noxious weed that smells like rotting flesh and dirty, old gym socks.
“If we keep letting it go, it’s going to eat the whole country up,” said Rod Cook, La Plata County weed manager.
The noxious flowers create a monoculture where no other plants can grow. Deer and elk prefer not to eat the flowers, and they produce a natural nerve agent that wards off pollinators, such as butterflies, Cook said.
“It creates a biological desert,” he said.
The noxious weed, found in the mountains across Colorado and in other states, escaped from wildflower gardens, said Steve Ryder, the state weed coordinator.
They are now illegal in the state, although it’s difficult to regulate sale of the flowers on the Internet, he said.
The white flowers are especially visible along U.S. Highway 550, Purgatory Ski Resort and along U.S. Forest Service roads in the Hermosa Creek drainage, where Cook and his team have been working for the last month to combat the problem.
The wet spring left the weed managers at a disadvantage all across the state because it is impossible to keep herbicides on the plants if it is raining, Ryder said.
Locally, nine Southwest Colorado counties and a handful of government agencies and private entities have formed a San Juan Mountains Cooperative Weed Management Area this year to fight oxeye daisy, Canada thistle and other noxious weeds.
The group plans to treat weeds along 109 miles of road this summer with the $40,000 it received this year from the state.
So far, the group has treated about 8 miles of road along Lime Creek Road, Relay Creek Road and Cascade Divide Creek, Cook said. They are starting work in the headwaters of the Hermosa Creek to prevent the seeds from spreading downstream. They apply broadleaf herbicides to the daisies on 15 feet on either side of the road to help keep the weed from being spread by vehicles, and they are trying to target smaller patches to stem the spread.
In one area, however, they needed to treat an infestation that had spread 125 feet from the road in the hopes of keeping it out of Relay Creek, he said.
The cooperative is also working with a Forest Service crew that is treating the daisies in Hermosa Creek Park, along Coal Bank Pass, Molas Pass and at the Pine River Trailhead near Vallecito Reservoir, said Justin Marler, a range technician.
His small crew of four is focusing on spraying daisies along trails, in campgrounds, and in corral and in other hotspots where people and animals could easily carry the seeds into the wilderness.
But the Forest Service has limited funding.
“We truly do need more partners,” he said.
For example, he is hoping the new ownership at Purgatory will be interested in working the Forest Service to treat their infestation of daisies.
In most cases, the weed managers’ only choice is to use herbicides on the weed, Ryder said.
Because the daisies are perennial, they can’t be dug up because they will regenerate, he said.
Herbicide treatment can give native plants a chance to reclaim the landscape over time. The cooperative is mapping all the areas that have been treated and the amount of herbicide used so they can monitor their success.
In some areas, the group is hand-spraying to protect the native plants from the herbicide, said Ben Bain, a geographic information system analyst and weed technician for La Plata County.
While nearly 109 miles of road sounds ambitious, it is only a small piece in the 5.5 million acres in the weed-management area.
Oxeye daisies have been spreading across the region since 1995, and Cook estimates it will take 20 years to see a reduction.
Ryder would like to see the management area expand to include more agencies so they can collaborate to identify infestations of oxeye daisy and other weeds earlier.
But the group’s progress will depend somewhat on grant-funding and donations that they can now accept through the La Plata County Conservation District.
Cook plans to start fundraising at the La Plata County Fair, which begins next week.
“If you do nothing with the invasives, you’ll just continue to lose native plants and habitat,” he said.
mshinn@durangoherald.com
How to avoid weed’s spread
The weed grows 10 inches to 2 feet tall.
Flowers bloom from June to August.
Flowers are 1-3 inches in diameter with 15-30 white ray flowers.
Each flower head can produce 200 seeds.
Seeds may be viable for 38 years or more.
Oxeye daisy can reduce native plant diversity and degrade pastures and natural areas.
It grows in mountain meadows, grasslands, pastures, along streams, in gardens and along railways and roads.
Because it is attractive, oxeye daisy is included in many seed mixes, so consumers should read the label before planting so-called “native wildflower mixes.” The seed is sometimes called Leucanthemum vulgare.
Goats or sheep can be effective in the control of oxeye daisy.
