Budbreak and winter injury in exotic firs

Abstract

Seventeen Abies species were evaluated for budbreak and frost injury at four locations in Michigan. Freeze tests were conducted on four species growing at the Horticulture Teaching and Research Center to determine cold hardiness levels during winter. Species differed (P ≤ 0.0001) in their days to budbreak at all locations. Trees that had broken bud were more prone to late spring frost damage than trees yet to break bud. Species differed in chlorophyll fluorescence, bud damage, and needle damage after exposure to -44 °C. Bud, foliar, and cambium damage were correlated with chlorophyll fluorescence following freeze tests. Budbreak and midwinter cold hardiness were correlated. Species breaking bud earlier displayed greater midwinter cold hardiness than species breaking bud later. Selection criteria for future Abies introductions to the upper midwestern U.S. should include identifying species with late budbreak to reduce risk of late frost injury.