Q&A Tuesday: When a good weed goes bad: noxious nonnative speciesPhoto:4211040,left;

What may be common plants in other parts of the world are often considered weeds here, and they're becoming more of a problem, according to farmers, land managers and wildlife advocates. According to the Invasive Weeds Awareness Coalition, nonnative plants have infested an estimated 100 million acres in the United States and displace native species by 8 to 20 percent each year.

Along with increasing efforts by public land management agencies to keep an eye on millions of U.S. acres, residents are encouraged to get in on the fight against weeds as well. State law mandates property owners keep their own land clear of the most noxious nonnative plants. Earlier this year, the federal government passed its own Noxious Weed Control Act, enabling the U.S. Department of Agriculture to assist weed management agencies.

JoAnne Skelly a University of Nevada, Reno Cooperative Extension educator, is an expert on invasive weeds, the damage they cause and how to fight them.

How do invasive and noxious weeds affect land around Carson City?

No other plants can compete. Noxious weeds reduce wildlife and fish habitat and food sources. They choke streams and waterways. They crowd out native plants and grasses. They decrease grazing potential and quality. There can be economic losses from refusals of hay shipments and decreased crop yields.

Finally, they are hugely expensive to control and take years of commitment to bring lands back to productivity. Some are toxic to wildlife or humans. They decrease property values. They impair wetland functions and increase erosion. Noxious weeds can increase habitat for vermin such as mosquitoes. They affect recreation. They alter fire regimes and can lower water table depths.

How prevalent are various types of weeds here?

The noxious weeds we are most concerned about in Carson City are: tall whitetop, Russian knapweed and hoary cress. The city has been battling tall whitetop for years, and each year reduces the infestation a little while trying to control spread into new areas. The city sprayed 85 acres for tall whitetop in 2004-05 and 45 acres of Russian knapweed in Kings Canyon.

Estimates indicate that weeds have invaded approximately 17 million acres of public rangelands in the West, more than quadrupling their range from 1985 to 1995. In Northern California, yellow starthistle spread from 1 million acres in 1981 to 10 million acres today.

What brings nonnative species in to a new place?

They come in on fill soil, vehicles, clothes, shoes, tents, etc. They come in on infected hay and feed. Seeds travel by wind and water, on wildlife, horses, livestock and people. Floods spread contaminated soil, root pieces and seeds downstream.

What makes land more susceptible to invasive weeds?

Disturbed sites are very susceptible, particularly when native vegetation has been destroyed and there is nothing to compete with the weeds. Weeds are very competitive and do re-establish more quickly than native plants.

How susceptible is the land around here?

There are acres of Russian knapweed at the northwest end of town behind Glen Eagles and in Kings Canyon. There is tall whitetop in many locations. But we are in better shape than some communities, because the infestations are relatively small and still manageable. The city maps infestations every year and sprays city property twice per year.

How does one fight the plants?

Unfortunately, noxious weeds are hard to control. Pulling usually just spreads more, unless a person pulls many times through the year and does it for years on end. Mowing is not an option because it spreads the weeds by roots. Chemicals are often the only remedy. Many years of committed spraying and monitoring is needed.

Is there anyone a person battling noxious weeds on their own land could contact for help?

I'm the coordinator for the Carson City Weed Coalition and would be happy to help people. (Her number is 887-2252, or e-mail skellyj@unce.unr.edu)