It still remains the number one threat to the industry, according to industry leaders themselves. Eastern filbert blight came to Oregon after its introduction to Clark County, Washington, just across the Columbia River from Portland. In the early 1980s, spores probably hitched a ride on a northern wind. Movement of the disease appears to be associated with rain events of longer than five hours. If left untreated and the afflicted trees left unpruned, eastern filbert blight can probably render an orchard unproductive within 10 to 15 years.
Officials calculate the disease is moving south at about a couple miles per year on average.
More than a third of that production area is now affected and subject to an ODA quarantine, designed to keep any spread natural. The last thing needed is an accelerated man-made spread of the disease through movement of plant material. In late 1995, ODA established an emergency quarantine restricting retailers and wholesalers of ornamental filbert stock from selling such stock within the state. Agreement on a statewide quarantine was reached through cooperation between ODA, the Oregon Association of Nurserymen, and the Oregon Hazelnut Commission. The moratorium on retail sales of filbert trees within Oregon is scheduled to expire in January.