Winter Injury to Fruit Buds of Stone Fruits in Washington

Abstract

A cold wave brought below-zero temperatures to a large part of the Pacific Northwest in late December of 1968. A minimum temperature of -11°F was recorded on December 30 adjacent to the Roza Unit orchards of the Irrigated Agriculture Research and Extension Center in the Yakima Valley, near Prosser, Washington. The weather preceding the freewe was relatively mild with maximum temperatures in the 30's and minimums in the 20's. Under these conditions, fruit tress are relatively susceptible to low temperature injury.

A large number of stone fruit varieties and selections are maintained at the Center primarily in connection with the stone fruit breeding program. After the freeze the Center orchards were surveyed to assess fruit bud losses. Brnaches were cut and brought into the laboratory. Fruit buds were cut crosswise and examined for browning. Discolored buds were considered dead. Where two or more trees of a variety or selection were sampled, the mean percentage of bud survival was calculated.