The influence of defoliation on flowering dogwood

Abstract

Forty flowering dogwood trees were subjected to 1 of 5 defoliation levels (0% , 25%, 50%, 75%, and 100% defoliation). Defoliation impact was assessed by measuring changes in diameter, twig extension growth, and electrical resistance of the cambium. Electrical resistance in the cambium increased for plants that were totally defoliated. Circumference growth of flowering dogwood was reduced 50% by total defoliation when compared to defoliated plants. Twig extension growth of defoliation stressed trees was reduced ⊕ 35% as defoliation levels reached 75% and 100%. Both increases in circumference and twig extension growth are affected by defoliation stress. Twig extension growth is the best measure of defoliation stress because it has the advantage of not requiring wounding when used to assess the impact of defoliation stress after the fact.