Tamarisk poised to become green rash?
When Stephen Elzinga takes a drive through Eagle County, he rarely appreciates the views.
Instead, his eyes focus on finding and eradicating invading plants that are spreading across the county. Elzinga is Eagle County’s weed and pest coordinator and high on his radar screen this year is tamarisk, an invasive shrub from Eurasia that has bright green foliage and a billowy pink flower and is quickly spreading up the county’s two main watersheds.
It was originally introduced as an ornamental and stream-bank stabilizing tree in California and Arizona in the 1880s. Now it’s out-competing native fauna and displacing flora. You might be surprised how far and how it is spreading. It has no predators or diseases to check its spread.
“It’s disconcerting,” he said. “In the last two years I have found small tamarisk seedlings a mile or two from where I knew there were other plants.”
He’s removed tamarisk in Edwards along Interstate 70 and has even found a tamarisk seedling growing along side the Squaw Creek Road. He’s found seedlings in both the Gypsum and Brush Creek valleys.
More troubling, however, is the discovery that the plant is being used as an ornamental at one home in Singletree. Each shrub has the ability to create new plants with new sprouts or by releasing tens of thousands of tiny airborne seeds.
They can even be spread by humans. Tamarisk seeds can stick to boats and waders and can be deposited hundreds or even thousands of miles from where they were picked up. Some seeds can be inadvertently transported in dirt adhering to earth moving equipment, too.
Eagle County’s water-loving tamarisk stands probably total 25 acres at present, Elzinga said, and most of those are centered along the Eagle and Colorado rivers. It’s a pretty recent arrival.
“This summer I cut one tree down,” he said. “It was 19- or 20-years-old.”
It has not yet clogged those valleys to the extent is has farther down the Colorado River watershed in places like Grand Junction or near Moab, Utah. There, the dense galleries of tamarisk line riverbanks and are virtually impenetrable.
The plant doesn’t care about governmental boundaries so fighting it takes a combined public and private effort, Elzinga said. The Bureau of Land Management has spearheaded and coordinated many of the control efforts along the Colorado River.
Gov. Bill Owens last January ordered that Colorado get tamarisk under control within a decade. State lawmakers are considering up to $1 million in funding for controlling tamarisk. Members of Congress, including U.S. Rep. Scott McInnis, R-Grand Junction, also have introduced legislation funding tamarisk control efforts.
Battling the invader, however, wont’ be cheap. Hand cutting and herbicide application can cost up to $5,000 per acre and burning the stands only seems to cause them to redouble their growth.
Eagle County does not have a separate budget for tamarisk control. It still falls under the county’s $128,000 annual noxious weed and pest control budget, Elzinga said.
In some circles, tamarisk is decried for sucking up far more water than native willows and cottownoods. But that may or may not be true, Elzinga said. Both use plenty of water, but tamarisk will grow in some areas native plants typically will not, he said, like along the edges of reservoirs.
“At one time it was accepted fact that tamarisk used more water,” he said. “Some scientists are now saying it uses an amount comparable to native species.
Like most environmental issues, there’s an endangered species hanging in the balance – the southwestern willow flycatcher – that has begun to rely on tamarisk instead of the willows that tamarisk has replaced, for nest sites. The fear is that removing tamarisk will reduce the available nesting habitat, further imperiling the estimated 400 remaing native songbirds.
Some Western states, including Colorado, are experimenting with a biological approach to battling the invader. They’re introducing, under controlled, settings, the Chinese leaf beetle, which munches the plant, and the Israeli mealybug, which chomps the plant’s stems.
Elzinga said the bugs are confined to cages placed in tamarisk groves. In tests, the bugs have proven an effective natural control to the introduced shrub.
“Where they’ve had biological control in Nevada,” Elzinga said, “it has really knocked the trees back.”
But introducing the bugs, like introducing tamarisk, could produce unintended effects.
“It’s a big deal to get a bug approved (for treatment),” Elzinga said.”There is a long, complicated safety process to make sure the bug will be weed-specific so it doesn’t become a bigger problem.”
If you have questions about tamarisk or other noxious weeds, call Elzinga at 328-3544.
Sidebar: One successful tamarisk battle
With its legendary ability to proliferate, it may seem fighting tamarisk is a losing battle. But it doesn’t have to be.
In one California desert nature preserve, a successful war was waged against the invader. At the Coachella Valley Reserve, tamarisk had invaded a pristine 25-acre wetlands, forming dense galleries that shaded out all other species of plants. Reserve managers decided to act.
“You have to be very strategic about it,” said Cameron Barrows, former director of the preserve. “It does take a high degree of intensity to be successful.”
The removal effort relied upon volunteer labor, Barrows said. Tamarisk that covered 70 percent of the wetlands were cut and the stumps were immediately sprayed with herbicide.
“You have to spray the stump within two or three minutes,” he said. “It doesn’t work very well if you wait.”
After the first removal effort, volunteers would at two-week intervals walk through the wetlands, pulling out new sprouts and removing any re-sprouted plants that survived the first cutting.
“It really was just weekend work that took probably 10 weekends a year for five years,” Barrows said. He estimates it took 400 people-hours a year to remove tamarisk from the wetlands.
Once tamarisk is removed, the native willows and cottonwoods are quick to revegetate the area.
The tamarisk were so thick, and thirsty, Barrows said, that they stopped the flow of a spring-fed creek. That flow returned within days of removing the tamarisk.
Cliff Thompson can be reached at 970-949-0555 x450 or firstname.lastname@example.org
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