Walnut growers across Butte County are reporting a smaller crop this year as harvest season winds down, with unusually warm spring temperatures believed to be a key factor. The Butte County Farm Bureau said growers have reported yield decreases ranging from 15% to 20%, based on their individual experiences in the fields. Officials feel that higher market price will offset the lower production yield. Butte County is the state's second-largest walnut-producing county behind San Joaquin County.