Variation in the phenology of bud flushing in white and red spruce

Abstract

Variation in bud flushing date as related to degree-day accumulation was determined among seed sources, families, and individual white spruce (Piceaglauca (Moench) Voss) trees in both a provenance study plantation and a progeny test of select trees on the Penobscot Experimental Forest in north central Maine. The primary purpose was to determine the feasibility of improving resistance to spruce budworm defoliation by selection for late bud flushing. Comparisons with native red spruce indicate that while some improvement in late flushing may be possible, it is unlikely that late flushing dates comparable with the mean for native red spruce can be achieved for white spruce.