Examples of Idaho Invaders and Threats

ALREADY HERE

A. White pine blister rust, (Cronartium ribicola) was introduced from imported nursery stock about 1900. This forest pathogen has decimated northern Idaho’s famed white pine stands, costing billions in lost timber values and in control efforts. Foresters now propagate white pine trees that are bred to be resistant to the fungus and reintroduce them into the forests. But fears are the fungus could mutate and attack now-resistant trees.

B. Tansy ragwort (Senecio jacobaea), a Eurasian weed first reported in Oregon in 1922, spreads primarily by seed. A single plant may produce up to 150,000 seeds, which may remain viable for up to 15 years. All parts of the weed are poisonous. It causes liver damage to cattle and horses; sheep are affected to a lesser extent. It is widespread in northern, central, and southeastern Idaho.

C. New Zealand mudsnails (Potamopyrgus antipodarum) appeared in Idaho’s Snake River in the 1980s and are now being studied by UI scientists in prime trout streams including Silver Creek, south of Sun Valley. Mudsnails can reproduce quickly and mass in high densities, causing concern they will impact the food chain of native trout and even alter physical characteristics of trout streams.

AT OUR BORDERS

D. Zebra mussels (Dreissena polymorpha) could cost millions to our hydropower, agricultural, recreation, and water supply industries, and could severely impact native fish, wildlife, and plant communities. One that had traveled through Idaho aboard a boat trailer was spotted recently at a Spokane entry station. Idaho participates in the 100th Meridian Initiative, a cooperative effort between state and federal agencies to prevent its westward spread.

E. Asian gypsy moth (Lymantria dispar) feeds on foliage of more than 500 species of trees and shrubs. Losses in the U.S. have averaged $30 million a year. Egg masses are commonly carried from infested areas on camp or boat trailers. A major invasion pathway is Idaho newcomers from infested states. Idaho State Department of Agriculture (ISDA) figures 10,195 new residents moved to the Gem state from infected areas between May 2002 and April 2003. In 2003 ISDA placed 5,582 detection traps, many in neighborhoods of these new residents.

F. Potato cyst nematodes (Globodera pallida) scared Idaho and the nation’s potato growers in April when two pinhead-sized cysts detected in a soil sample from an Idaho potato processing facility may have been PCNs—the first find in the nation. Intensive tests as of press deadline had found no other sign. Since 2003, the UI had conducted more than 9,000 soil sample tests in Idaho’s potato growing region—all negative. PCN is one of 400 pests routinely tracked in the USDA’s Cooperative Agricultural Pest Survey (CAPS).

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