Jefferson EFB Resistant Hazelnut Trees

hazelnut“Compared with ‘Barcelona’, Oregon’s leading cultivar, ‘Jefferson is a smaller tree, with higher nut yield and much higher nut yield efficiency.”
– excerpt from April 2011 HortScience article


Jefferson Hazelnuts

About the Nuts: In-Shell Market Takeover
Jefferson has quickly become the most widely planted new release out of Oregon State University. And, according to the 99th Nut Growers Meeting held in January 2014, growers of this newer cultivar are very excited about its performance so far. Early commercial plantings are coming into full production and processors like what they see as well. With the results of the fall 2013 harvest, prices paid for Jefferson nuts rose considerably, which led to even more new Jefferson orchards going in last fall and this spring.

Jefferson’s initial appeal came from its marketing as an EFB resistant replacement of Barcelona. Serving the in-shell market, for which Oregon hazelnuts are famous for, Jefferson was recognized early for its large nut size, high yields and overall good nut quality. Another of Jefferson’s strengths is its upright, open growing habit. This allows for good light penetration into the canopy which can increase nut set, nut size, and kernel size and reduce the occurrence of single-nut clusters. Early trials further proved the benefits of a more open canopy, showing higher marketable yields in Jefferson than in Barcelona as well as less kernel defects, greater kernel uniformity and lower incidence of kernel mold. All of this translates into bigger profits for growers.


Mature Jefferson Hazelnut Tree Jefferson tree at the OSU test plots in Corvallis

About the tree
As early Jefferson plantings are maturing some growers have noticed cankers, an early warning sign of Eastern Filbert Blight. However, unlike other cultivars infected with this fungus, Jefferson trees seem to fight off the infection and recover. This is something growers and researchers are monitoring, but at this point they are not too concerned with the development. For now growers are encouraged to keep planting Jefferson, and other varieties with “Gasaway” resistance, but to also keep an eye out for possible EFB infections.

Pollination, Bloom Time and Harvest
When Jefferson was first released, effective late-season pollinizers were still in the development and testing stages so many new orchards were planted without complete pollen coverage. As could be expected, this lack of late pollen impacted early commercial yield data. However, with the release of Felix in 2012, growers were finally able to effectively cater to Jefferson’s pollen needs. Jefferson has a very late female bloom time, not starting until the middle of January. But, it is quite drawn out, lasting until early March. This requires very late pollinizers. Oregon State University recommends the following as pollinizers for Jefferson: Felix (20%), Eta (20%) and Theta (60%). Most other varieties shed pollen too early for Jefferson but York and Gamma can be used for earlier pollen if desired. Jefferson expresses alleles 1 and 3 in female flowers but only allele 3 in its pollen. Jefferson is a suitable pollinizer for Dorris, Wepster and Yamhill. Jefferson harvest is the latest of the widely planted cultivars, usually a few days after Barcelona.