Noxious weed attacks! |

Noxious weed attacks!

by Sharon Carter

Lanky stems terminating in dense clusters of small white flowers rustle stiffly in the breeze along stretches of Steamboat Creek and the lower Truckee River. Common along rivers and streams throughout the West and much of the Midwest, tall whitetop has become a problem in several areas in western Nevada.

Now, it has begun to invade the Carson River.

Several small colonies of the plant along the Carson have area ranchers and conservationists worried. The blossoms look harmless enough – somewhat like the tiny, frothy “baby’s breath” used in spring bouquets and floral arrangements.

They aren’t.

Also called pepperweed, the delicacy of its flowers belies the tall whitetop’s rapacious underlying nature. A wild Eurasian mustard likely brought into the U.S. in sugar beet seed and dried flower arrangements sometime after the turn of the century, tall whitetop crowds out the native willows and cottonwoods that hold the stream banks together and provide cover and food for waterfowl and other birds.

It easily spreads to neighboring fields of Timothy grass and alfalfa, degrading the hay and reducing its value as animal feed. It is also a nuisance in residential areas, on golf courses and along roadsides where its thick stands of stiff, woody stems make walking or moving equipment nearly impossible.

And it is difficult to eliminate.

“This is as close to being an unstoppable alien invasion from another planet as anything I’ve ever seen,” said Dan Kaffer, of the Western Nevada Resource Conservation Development Council. “There are ways to control most alien species, but treating this weed is extremely difficult. They’re researching it now at the Tracy Power Plant (on the Truckee east of Reno) and at the University of Nevada, Reno’s research farm in Reno.”

Because its leaves and stems are covered with a waxy layer, chemical treatments must be timed properly or the effort is wasted. Since it grows on stream banks, spraying with weed killers risks contaminating the water. Mechanical methods of destroying the plant – chopping and burning – actually encourage it, stimulating the spread of the plant’s root-like stems, called rhizomes, along the ground. Cut pieces of the rhizomes smaller than a quarter of an inch in length will take root and grow.

An acre of the pretty little white flowers can produce an estimated six billion seeds a year, live seeds that can be carried by wind, water and animals (including humans) to other areas.

Kaffer said the researchers estimate that each acre of tall whitetop takes about four acre-feet of water from the land per year.

“There are about 12,000 acres of wet meadows and alfalfa fields on the Truckee that have been overrun with tall whitetop,” he said. “It can take over a yard, a pasture or a ranch. So far, the best way of stopping it, is not to let it get started. But, of the five counties on the Carson River, only two have weed control programs.”

Not letting tall whitetop get started is a project Douglas County weed control officer Larry Hughes and his two seasonal crews have been working on since last year.

“In Douglas, we have pockets of tall whitetop along the Carson and its West Fork,” Hughes said Thursday. “There’s a pocket on the river about a mile north of the California line and another above the horseshoe bend. We treated them last year and got a good start on controlling it. It looks like we got about a 50-percent kill, which is not bad for a first year spray.”

Hughes, who has been killing noxious weeds in Douglas for four years and spent another 18 years doing the same thing in California, said the county program was in place when he came here.

“We have had a weed program for years. Without it, we’d be facing the same problems the others are facing,” Hughes said. “We have a little bit of a head start, so we don’t have to begin from ground zero buying sprayers and equipment.”

The problems with tall whitetop Hughes referred to are on the East Walker River as well as the Truckee. On the Walker, tall whitetop has been found near Bridgeport at elevations of 7,000 feet.

The weed colonies have been found downstream on the Carson, where last year’s flooding from the Truckee carried it to the lower Carson via the Derby Ditch near Fallon.

Jane Schmidt of the U.S. Department of Agriculture’s Natural Resources Conservation Service office in Gardnerville said new tall whitetop colonies on the lower Carson pose a serious threat to the Stillwater Wildlife Sanctuary.

“It is really of extreme concern, we’ve not seen tall whitetop to a large degree on the Carson yet, but by the time you see a big problem, it’s too late,” Schmidt said.

She likens the invasion of tall whitetop to an “explosion in slow motion.”

“With our last few wet years, the weed problem is starting to explode in our area,” Schmidt said. “Tall whitetop and short whitetop (hoary cress), Canada and yellow star thistles, Russian and diffuse knapweeds and puncture vines are all noxious weeds that grow exponentially – plant colonies start in a growth pattern of doubling or tripling each season and off you go.”

She said the plants came to this country without the natural controls that were present in their native regions.

“Minus the rest of their natural ecology, all we’re seeing is explosion,” Schmidt said. “We’ve seen knapweeds destroy 5 million acres of elk habitat in Montana. The purpose of our meeting Tuesday is to decide on an approach in educating people about these weeds and what they can do. Landowners have to understand the problem will affect all the neighbors – the upstream sources send the problem downstream. And once something like tall whitetop gains a foothold, it’s prohibitively expensive to treat. Communities need to be ready to take a firm stand and use their quarantine authority if they have to. When noxious weeds are located, treatment has got to happen. With tall whitetop on the Carson, we still have a fighting chance.”

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