The Yamhill walnut cultivar was developed by the Oregon State University in 2008. The bushes of this variety are compact, with crowns 12% smaller than those of the Barcelona variety, which promotes good light penetration and optimal plant growth. Despite its smaller growth vigor and compact bush structure, Yamhill is distinguished by high yield, surpassing many other varieties. The nuts are harvested in clusters of 4-5, have a light-brown shell with a small amount of husk, making them appealing when eaten raw. The average nut mass is about 2.3-2.5 grams, kernel mass is 1.1 grams, and kernel percentage reaches 49%. The nuts blanch well and easily detach from the husk at full maturity. Yamhill is an early-maturing variety, ripening 10-14 days earlier than Barcelona, typically at the end of August to early September. Flowering occurs simultaneously with the Wester and Sacajawea varieties, which is important for proper pollination, as Yamhill requires pollinators. Recommended pollinators include Sacajawea, York, Gamma, Doris, Wester, and Jefferson. The variety has high cold tolerance, surviving temperatures from -18 to -25 °C, and does not require winter protection, simplifying care and increasing reliability in cold-hardiness zones 6b-8. The plant reaches a height of up to 5 meters and prefers neutral soils, planted in sunny or partial shade areas with a spacing of 3-4 meters between bushes. The yield of this variety ranges from 6 to 10 kg per bush, and the first fruits appear as early as the 2nd-3rd year after planting. Due to its characteristics and flavor qualities — nutty and sweet taste — the Yamhill variety is recommended for use in the confectionery industry. Additionally, the variety exhibits high resistance to the phylloxera mite, enhancing its pest resistance and reducing the need for treatments.
