| Abstrakt: |
AbstractDefoliation by the birch casebearer, Coleophora fuscedinellaZeller, the most important pest of white birch, Betula papyriferaMarsh., in Newfoundland, is correlated with leaf size but the differences in defoliation associated with leaf size are too small to be of practical importance. Thus, a sample of at least eight leaves from either the top crown quarter or from mid crown will give consistent estimates of tree defoliation, and 14 trees should be sampled to classify a stand for appraisal surveys or for evaluation of damage to scenic areas. Evaluation of stand defoliation in three broad classes is recommended: up to 30% defoliation appears as light browning not noticed by the general public, 30% to 90% results in distinct browning, and over 90% defoliation denotes intensive browning and bud and branch mortality. |
