Regional Bonsai Care: Defoliating

摘要

Mention the word defoliation to most gardeners and horticulturalists, and it conjures images of dying plants, accidents with pesticides, cotton harvesting or swarms of insects. But in bonsai, it is a valuable advanced tool to refine and improve our trees. However, to be safe and effective, the technique needs to be applied to the proper tree at the proper time. Defoliation, also known to bonsaiists as leaf pruning, has several purposes: 1) It provides a second new set of leaves which are smaller thanthe initial leaves, thus improving the dimension of scale and overall appearance of the tree. In addition, this new set of leaves has smaller internodes,thus allowing permanently more compact growth. 2) It stimulates back budding, releasing dormant axial buds from the suppressive effects of auxins produced in the leaves and growth tips. Back budding allows future reduction of branch length, selection of new branches, increased twigging, and better ramification. 3) Weak areas of trees can be strengthened by sparing the weak area while defoliating the remainder of the tree. 4) Defoliation can improve the general health of the tree by opening up inner areas to air and sunlight. 5) It improves autumn color of maples and other deciduous trees. 6) Occasionally it can be a useful method for eliminating difficult pests such as scale.