CORVALLIS, Ore. The Swiss needle cast epidemic in Douglas-fir forests of the coastal Pacific Northwest is continuing to intensify, appears to be unprecedented over at least the past 100 years, and is probably linked to the extensive planting of Douglas-fir along the coast and a warmer climate, new research concludes.
Scientists in the College of Forestry at Oregon State University have also found that this disease, which is affecting hundreds of thousands of acres in Oregon and Washington and costing tens of millions of dollars a year in lost growth, can affect older trees as well as young stands in some cases causing their growth to almost grind to a halt.
The newest findings were just published in Forest Ecology and Management, a professional journal.
Swiss needle cast is a native fungal disease specific to Douglas-fir that was first described in Europe. It rarely kills trees but causes discoloration, loss of needles and growth reduction, and is common in the Pacific Northwest wherever Douglas-fir grows. However, it caused significant problems only in recent decades along the coast.
Starting in 1984, an epidemic began to develop, and it significantly worsened after 1996.
"It's now clear that this epidemic is a new phenomenon, with far more severity and impact than anything we've observed from Swiss needle cast in the past," said Dave Shaw, an assistant professor at OSU and director of a cooperative designed to fight this disease. "We've known of this disease for decades but it was considered a non-issue in terms of forest health. A perfect storm of conditions that favor this fungus has caused a major epidemic that is still growing."
The disease has now been identified at varying levels of severity in western Oregon on more than 300,000 acres in each of the past four years, peaking at 376,000 acres in 2008. Prior to this four-year period, it had affected as much as 300,000 acres only once in the
|Contact: Dave Shaw|
Oregon State University