Hazelnut selection from Oregon State University with Gassaway resistance to Eastern Filbert Blight (EFB). Potential new cultivar expected to be released in 2009. Well suited to the in-shell market, it combines high yield, large nut size and a vigorous tree. Nut maturity is with 'Barcelona' or up to three days later. Requires a late-shedding polinizer. The Oregon Agricultural Experiment Station announces the release of a new hazelnut (Corylus avellana L.) cultivar 'Jefferson' for th in-shell market with high nut yields, attractive nuts and kernels, good kernel quality, resistance to bud mite (primarily Phytoptus avellanae Nal.), and complete resistance to eastern filbert blight caused by Anisogramma anomala (Peck) E. M ller. 'Jefferson' (OSU 703.007) resulted from a cross of OSU 252.146 x OSU 414.062 made in 1993. OSU 252.146 is a seedling from a cross of OSU 41.083 (= 'Montebello' x 'Compton') x OSU 17.028 (= 'Barcelona' x 'Tombul Ghiaghli'), and OSU 414.062 is from a cross of OSU 23.017 (= 'Barcelona' x 'Extra Ghiaghli') x VR 11-27 (= 'Montebello' x 'Gasaway'). Compared to the standard 'Barcelona', 'Jefferson' has smaller trees, higher nut yields per tree, and higher nut yield efficiency. Nuts of 'Jefferson' are large (3.2-4.2 g) and similar in size to 'Barcelona' (3.8 g) and have a slightly higher percent kernel (45% vs. 43%). About 80% of the nuts fall free of the husk at maturity and can be mechanically harvested with 'Barcelona' or up to 3 days later. The kernels fill the nuts well, which is unusual for a large nut. Raw kernels have a moderate to heavy amount of fiber on their pellicles, similar to 'Barcelona'. Blanching ratings are slightly better than 'Barcelona', indicating that slightly more than half of the pellicle is removed by dry heat. Kernel quality is suitable for many end uses, although they are larger than the size desired by most chocolate makers and bakers. The frequency of blanks, poorly filled nuts, and double is less than for 'Barcelona'. 'Jefferson' has a low frequency of moldy kernels, which was especially striking in 2005 when mold was a problem on 'Lewis' and many other genotypes. 'Jefferson' has more kernels with black tips than 'Barcelona', which i a reflection of the occasional hairline splits where the two halves of the shell join at the apex. 'Jefferson' has complete resistance to eastern filbert blight, conferred by a dominant allele from 'Gasaway'. 'Jefferson' appears to be susceptible to bacterial blight, as is 'Barcelona'. Copper sprays are recommended for control of bacterial blight. 'Jefferson' has incompatibility alleles S1 and S3, the same as 'Willamette'. Both alleles are expressed in the stigmas, but only S3 is expressed in the pollen. Pollen is shed in mid-season, but female receptivity is very late. Pollinizers that shed pollen very late are recommended. We recommend one-third of 'Eta' (S11 S26) and two-thirds 'Theta' (S5 S15). 'Yamhill' pollen is effective on early-emerging females of 'Jefferson', so planting orchards of two cultivars, alternating 'Jefferson' and 'Yamhill' at double density, is also an option.
'Jefferson' is being released as a public cultivar and may be propagated fo sale in the United States without restriction. A list of nurseries and micropropagators is available from S. A. Mehlenbacher, Department of Horticulture, 4017 Agricultural and Life Sciences Building, Oregon State University, Corvallis, OR 97331-7304. Small quantities of scion wood may be obtained from the same address. Legal protection for 'Jefferson' will be sought in Chile, and a licensing agreement pursued with a micropropagator and a nursery.
Shawn Mehlenbacher, Release notice for 'Jefferson' 2009.