EFFECT OF DEFOLIATION ON THE GROWTH OF TEAK

Abstract

In a one-year-old teak (Tectona grandis) plantation at Kaptai, Bangladesh, manual defoliation (25,50, 75 and 100%) in june, simulating the damage caused by the larvae of teak defoliator, Hyblaea puera Cramer (Hyblaeidae: Lepidoptera), was carried out. Four years of such defoliation caused significant losses of about 14-49% in height, 19-51% in basal area and 23-62% in volume increments depending on the intensity of defoliation as compared to the unsprayed control. However, the losses were about 28-57%, 53-72% and 58-79% respectively compared to the sprayed control. The sprayed control that excluded all potential herbivores afforded about 16% in height, 42% in basal area and 45% in volume increments against those of the unsprayed control. Loss of volume increment is a serious impact of defoliation. Protection during the early years would be advantageous because of the higher absolute increment of teak at this stage. None of the trees defoliated showed mortality or leading shoot dieback.