New UC Wolfskill Widens Harvest Window

A young UC Wolfskill tree. This new walnut variety was released by the Walnut Improvement Program at UC Davis this year. UC Wolfskill was originally planted and evaluated at UC Davis, and field trials with growers began in 2011 (photo courtesy Janine Hasey, UC WIP.)

Pushing the walnut harvest window open a little wider is the new UC variety “UC Wolfskill”.

This new walnut variety is the result of funding by California Walnut Board for the UC Davis Walnut Improvement Program. UC Wolfskill is the result of a 2003 cross of the Chandler variety and the early harvest Solano variety. UC researchers report that UC Wolfskill can be harvested 12 to 14 days earlier than Chandler.

More than half of the state’s bearing walnut acres are planted with late harvest Chandler variety, which was released in 1979 and is known for its yield and light kernel color. The release of UC Wolfskill will allow growers to spread out walnut harvest and still have the yield and quality similar to Chandler, said UC Davis plant breeder Patrick J. Brown.

UC Wolfskill was originally planted and evaluated at UC Davis, and field trials with growers began in 2011.

In addition to the early harvest trait and kernel fill from Solano, UC Wolfskill has color and shell traits of Chandler. Walnut handlers judge the value of a walnut based on its color and how well it halves while processing. In blind quality evaluations by commercial graders, the UC Wolfskill was often not distinguished from Chandler.

UC Wolfskill is now available to California nurseries for propagation in California and sales to growers throughout the United States. Nurseries interested in propagating and selling this cultivar may obtain a license from UC Davis InnovationAccess. To obtain a license, please contact Denise Meade at InnovationAccess by phone at (530) 754-8674 or by email at

“Variety and rootstock breeding is a long-term effort, and the walnut industry recognized early on that a stable source of support would be vital to the program’s success,” said CWB Research Director Joe Grant. “Our goal is to be a valued supporter to our grower and handler community by providing funding and research on walnut production that improves crop health and yields, ultimately benefitting growers.”

“The commitment of our walnut growers, as collaborators, is the foundation that makes this release possible. The Board is extremely grateful for the long-term partnership of our growers and UC in finding innovative solutions that help us solve for critical needs,” said Michelle Connelly, executive director of the California Walnut Board.