Early Season Defoliation of Bird Cherry Influences Autumn Colonization by the Bird Cherry Aphid, Rhopalosiphum padi

Abstract

Bird cherry trees Prunus padus which were artificially defoliated early in the season suffered significantly less damage from late season defoliators than those trees which were undefoliated or suffered only slight defoliation. In the autumn, trees with little or no early season defoliation were colonized with significantly greater numbers of the aphid, Rhopalossphum padi, than those trees which had suffered defoliation in excess of 50%. Defoliation also resulted in significant differences in leaf chemistry; nitrogen levels in leaves of defoliated trees being significantly greater at time of aphid colonization than in trees that had not been defoliated