Weed spreading through basin | TahoeDailyTribune.com

Weed spreading through basin

by Sally J. Taylor

A quite invader has gained a foothold in the Tahoe Basin and is now rearing its pretty white head.

The tall whitetop, labeled a noxious weed by agriculture and environmental organizations, is in bloom and its presence is more widespread than anticipated.

Sue Donaldson, University of Nevada, Reno Cooperative Extension water-quality specialist and a leader in the battle against the weed because of its impact in stream environment zones, recently looked at the spread of tall whitetop next to the Trout Creek Bridge near Al Tahoe Boulevard.

“I’m unhappy to see this much here, it’s more vigorous than I’d like to see it,” she said.

“People said it wasn’t going to do well in the Tahoe Basin (because of the acid soil and climate). But obviously that’s not true,” she said, pointing out the mature plants spreading down the slope into the meadow.

Signs of attempted eradication were already apparent. Local, state and federal officials were alerted in April to the danger. Near the meadow, bags and mounds of cut and pulled plants were piled for disposal.

“It’s a good first step,” said Donaldson, unsure of what organization had started the effort.

Rubbing the flower heads, she was relieved to discover green seeds rather than the rust color of mature seeds.

Each flower spray produces 9,000 tiny seeds and the “potential for disaster,” Donaldson said. In experiments, germination rates range from 30 to 100 percent.

Even more tenacious than the seeds are the underground rhizomes. Pulling plants out of the ground tends to break the rhizomes into pieces, she said. A piece one-tenth of an inch can grow into a new plant.

“This is an area I think they need to come in and spot treat (with herbicide,)” Donaldson said.

A water quality specialist, Donaldson does not easily embrace the use of chemicals. With the danger tall whitetop poses, it may be the best answer where the weed is well established. Properly applied, limited use of specific chemicals can stop the plant without working their way into the water table

“Can we afford to have the riparian areas in the Tahoe Basin converted to tall whitetop riparian areas?” Donaldson asked. “I think we can’t. In this case, the use of herbicides is balanced out by the need to protect our vegetation.”

Once established, tall whitetop crowds out native plants such as willows, sedges and grasses, that filter sediment and nutrients out of runoff and hold soils.

Donaldson and others commanding the war against tall whitetop are asking the public to keep a watch out for the plant and report sightings. “We need eyes and ears to catch that first plant (in an area),” she said. Hikers and cyclists who may see plants away from roads are especially needed.

Residents who discover the plant on their property are urged to resist the lure of its pretty white blossoms and mount an attack. Using the plant in flower arrangements is suspected of spreading the seeds.

On Saturday, University of Nevada, Reno educators hope Tahoe residents will phone-in tall whitetop sightings.

“We’ll never get it out of the Lower Truckee River (though it may eventually be controlled),” Donaldson said. “We may be able to get it out of the Tahoe Basin.”

Tahoe Daily Tribune E-mail: tribune@tahoe.com

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