Basin mission: Stop invasive weed |

Basin mission: Stop invasive weed

Sally J. Taylor

An enemy has invaded the Tahoe Basin, hitching rides in hay bales, imported soil, seed mixes, on trucks, in floodwaters and even flower arrangements.

On Wednesday, three dozen representatives of basin agencies along with concerned individuals gathered in a “war room” at the Lahontan Water Quality Control office to learn how to identify and stop the enemy plant, commonly called tall whitetop, a.k.a., lepidium latifolium.

The noxious weed’s attractive clusters of delicate white flowers on tall stems disguise its devastating capabilities.

The potential damage is of such concern that the Tahoe Regional Planning Agency is willing to make an exception to its ban on the use of herbicides in stream environment zones.

“We strongly discourage the use of herbicides in (stream environment zones) unless something threatens the riparian habitat,” said Larry Benoit, who represented the TRPA at the meeting. “With this particular species, we should allow and encourage (herbicide use on the plant).”

Preferring wet areas, tall whitetop can take over an area in a few years, choking out native vegetation. Yet it does virtually nothing to secure slopes, filter water or provide food for wildlife.

“It’s not a weed that is easy to control and it’s a real disaster when it gets in riparian areas,” said Sue Donaldson, water quality education specialist with the University of Nevada, Reno Cooperative Extension Department and a member of the Washoe County Tall Whitetop Task Force.

Tall whitetop has a foothold in Washoe County, replacing hundreds of acres of native vegetation. Now it’s spreading into fresh territory.

On the north shore of Lake Tahoe, tall whitetop has a toehold. On the South Shore it has been sighted along Pioneer Trail, behind Caesars Tahoe, in the Trout Creek Meadow and even in Desolation Wilderness.

It seems to have entered the area since 1993 or 1994, according to Benoit.

Authorities believe clumps also hide around homes where the unsuspecting gardener may encourage it as an easy alternative to baby’s breath.

Don’t, warned Donaldson.

At its seedling stage, tall whitetop has cabbage-like, blue-green leaves. In established clumps, the new growth is easiest to spot at the base of the previous year’s dry, woody stalks.

It quickly grows upward on 1- to 3-foot stems, with the potential to grow 8 feet tall. Those pretty white flowers produce 10,000 reddish seeds per plant. Some seeds hang on through the winter to scatter with each gust of wind.

Starting with one plant, an acre of land can be overrun in four years.

Although the seeds spread the plant across wide areas, it’s the underground rhizomes that make eradication difficult. Tilling under the plants only cuts the rhizomes into prolific pieces. One piece as small as one-tenth of an inch can produce a new plant.

Herbicides, specifically “2, 4-D,” applied carefully to get to the rhizomes and applied repeatedly over several years have provided the best hope for eradication.

Property owners can dig out small clumps themselves but all the pieces of the rhizome must be removed.

To prevent spreading tall whitetop, the plants should be disposed of at the site through burning or letting the dead stalks mat on the spot.

To stop the enemy before it becomes entrenched in the Tahoe Basin, the task force hopes everyone takes responsibility beginning with their own property and keeping a watch out for other clump locations.

Anyone interested in enlisting in active duty on a Tahoe Basin task force can contact Benoit at the TRPA office at 588-4547.

Sightings of tall whitetop clumps should be brought to the attention of Larry Hughes, weed control supervisor for Douglas County Parks & Recreation at (702) 782-5799.

For more information on tall whitetop or other noxious weeds in the area, contact Donaldson at the cooperative extension office at (702) 832-4150.

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