Pests and Disease

NASF Annual Report

The NASF Annual Report highlights accomplishments by the nation's 59 State Foresters and their staffs to advance policy, communications, and operations priorities that help protect and enhance America's "green infrastructure": trees.

Tree mortality in Lake Tahoe’s forests has increased drastically

Lake Tahoe’s famously clear waters continue to warm, and the surrounding forests face dire threats due to drought, disease and insects, according to the annual Tahoe State of the Lake report by researchers at UC Davis.

The second deepest lake in the United States after Crater Lake, Lake Tahoe has warmed by half a degree Fahrenheit each year for the past four years — 14 times faster than the historic rate, the report said.

Forester: Bark Beetles Getting Worse in Idaho

Bark beetle problems continue to worsen on Northern Idaho forest lands, a university forester says.

Drought stress from several years ago has led to the increased pressure now, said Chris Schnepf, University of Idaho Extension forester in Coeur d’Alene, Idaho.

Western pine beetles, pine engraver beetles, fir engraver beetles and Douglas fir beetles all are more active this year, he said.

“All of these bark beetles are native insects, they’re always around at some endemic level,” he said. “But when you have stand conditions that favor them, they start to take off.”

Invasive emerald ash borer gets closer to South Dakota

Ash trees in South Dakota are on the cusp of endangerment.

The emerald ash borer (EAB), a green beetle that feasts on the vascular tissue of ash trees, has been expanding from its original discovery in Detroit, Mich. It has killed hundreds of millions of trees in the United States in the past decade, expanding from the Great Lakes region in 1990 to 25 states today, including Iowa, Minnesota and Nebraska.

Drought, Bark Beetles Weaken California's Trees

California has more than 100 million dead trees in its forests, and there is no consensus on their impact on the environment or how to deal with them.
In November, the U.S. Forest Service said an aerial survey revealed that 36 million additional trees had died in the midst of a multi-year drought, bringing the total since 2010 to more than 102 million.

The tree deaths have been concentrated in the southern and central Sierra Nevada, but experts warn of increasing deaths in forests all the way up to the Oregon border.