For growers who can't wait that long, OSU plant breeder Shawn Mehlenbacher released one moderately resistant variety early this year and will soon have another that combines some blight resistance with good yields and excellent kernel quality. Meanwhile, resourceful growers must use a combination of scouting, pruning and fungicides to keep good trees around as long as they can. That costs money, though, and many who have had the blight in their orchards more than 10 years could be forced out of the business unless they pay the cost of extensive replanting. Working with Mehlenbacher is OSU plant pathologist Kenneth Johnson, who has learned how eastern filbert blight works and is helping growers manage orchards to keep trees growing well as long as they can. Eastern filbert blight is spreading southward in the Willamette Valley and has reached the communities of Aurora and St. Paul.
Uncontrolled blight produces cankers that girdle branches and limbs, eventually killing the tree.
A recent OSU survey of 141 growers showed 98 percent of those with diseased orchards are employing one to several cultural control methods. These include pruning, replacing diseased pollinator trees, and removing volunteer seedlings. Eighty-eight percent of these growers are applying fungicides at least once per season. All that effort has its costs. Many growers don't have the energy for all the work, nor the money because of low hazelnut prices.