Introducing a Butte County Walnut Variety Trial

Becky Wheeler-Dykes, Orchard Systems and Weed Ecology Farm Advisor, Glenn, Colusa, and Tehama Counties

A ten-acre Butte County Walnut Variety Trial was planted at the Chico State Farm in May of this year. A collaboration between Chico State, UC Davis Walnut Improvement Program, and UC Cooperative Extension, this variety trial aims to identify new varieties that will perform exceptionally well in this region. The orchard is being managed using conventional practices that are currently industry standard for Chandler production. Eighteen new selections developed by the UC Walnut Improvement Program are planted in the replicated trial, along with Solano, Wolfskill, Howard, and Chandler. All trees are planted on RX1 rootstock on a 26’ X 26’ spacing with micro-sprinklers. The selections were chosen for qualities including kernel color and size, yield, blight ratings and late flowering dates in preliminary greenhouse and small plot field trials. Early bearing, long-term yield and nut quality, resistance to and avoidance of walnut blight, as well as heat tolerance will be monitored over the next several years.

Generous support from the Walnut Board of California, Sierra Gold Nurseries, Crain Ranch, M&T Chico Ranch, and the staff and management at the CSUC University Farm made this project possible. Additionally, the variety trial was recently awarded funding by the CSU Agricultural Research Institute, which will support ongoing field operations, student involvement and training on the farm, and data collection and testing in the field. We will provide periodic updates on the progress of the variety trial and host field meetings in the years to come, but if you’d like to learn more, please contact Clarissa Reyes, Orchards Farm Advisor based in Yuba/Sutter Counties at or Becky Wheeler-Dykes, Orchard Systems and Weed Ecology Farm Advisor based in Glenn County at


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