Eastern filbert blight has proven itself as the biggest nemesis of Oregon's official nut.
First discovered in western Washington in the 1970s, it later was found in Oregon's Clackamas County in 1986. The disease, which causes cankers and die-back on branches, is found on hazelnut trees -- also known as filbert trees -- throughout the Willamette Valley.
But gardeners with small-scale orchards can take advantage of hazelnut varieties bred in recent years at Oregon State University that resist the disease, said Jeff Olsen, a horticulturist with the OSU Extension Service.
He recommends the OSU-developed blight-resistant cultivars Jefferson, Yamhill and Dorris, a variety released in 2012. These varieties, particularly Jefferson and Yamhill, are beginning to be seen at retail nurseries, Olsen said.
Each variety is similar in taste but the size of the nut varies, with Jefferson being the largest and Yamhill the smallest. Dorris is thin-shelled, round and small. Its raw kernels, the edible part of the nut inside the hard shell, have good flavor. Yamhill kernels are good for chocolate and baked goods when lightly roasted. The low-maintenance Jefferson produces a tasty, large kernel.
Weston Miller, an Extension horticulturist, said if you're going to grow hazelnuts, be prepared to be in it for the long haul.
"I would not necessarily recommend that home orchardists grow hazelnuts because the yield is pretty low per tree and it is a longer-term investment," Miller said. "Though for big hazelnut fans, it could be fun. Hazelnuts are quite ornamental and would look nice in an edible landscape. I'd definitely recommend the new dwarfing and disease-resistant varieties."
Blight-resistant varieties of hazelnut trees are fairly easy to grow, especially in Oregon, which boasts about 99 percent of the U.S. commercial production, Olsen said. Hazelnut trees that are susceptible to eastern filbert blight, however, require more maintenance. They must be sprayed with fungicide four times in the spring at two-week intervals.
The trees can be planted anytime from fall to spring, during the dormant season. January and February are good months to plant.
Hazelnuts thrive in deep, well-drained soils, with Willamette silt loam named one of the best.
Hazelnut trees require cross-pollination, so choose "pollinizer" trees that are resistant to eastern filbert blight and can offer compatible pollen for your main variety. Good pollinizers for Jefferson are Felix, Eta and Theta. For Yamhill, choose Gamma and Santiam. For Dorris, choose York and Felix.
Prune the trees during the dormant season. Aim for maximum sun exposure on the tree.
The trees need to be fertilized mostly with nitrogen, potassium and boron. Hazelnuts must be watered in the first couple years but irrigation is not needed afterward. Trees can survive for decades, unless disease strikes.
You'll be able to harvest your hazelnuts in the third or fourth year, rewarding your patience by giving your favorite chocolate torte recipe that extra nutty pizazz.
To learn more, a guide to growing hazelnuts in the Pacific Northwest is available from OSU Extension for $4 at http://bit.ly/Vi8i49. An Extension guide to managing pests and diseases in home orchards is available for free at http://bit.ly/13B3s5Y.