Sweet cherry production in the Sacramento and southern San Joaquin valleys of California has historically been limited by excessive fruit doubling on the commonly grown cultivars. High summer temperatures at the time of flower bud differentiation are generally believed to cause double pistils to form, resulting in many double or spur (one side of the double aborted) fruit at harvest time the following year. Double and spur fruit are considered culls in commercial market channels, and they tend to be more prone to decay than normal cherries.

The assistance of Kay Ryugo, Department of Pomology, U.C., Davis, and Larry Bettiga, Staff Research Associate, Parlier, is gratefully acknowledged.