Defoliation refers to the process when a tree or shrub loses its leaves. There are many reasons why leaves may be lost. Possible causes include chemicals, pests, diseases, environment and (for deciduous trees and shrubs) autumn.
Defoliation can be quite a problem for trees and shrubs. The plant uses the chlorophyll in leaves to create energy through photosynthesis. Fewer leaves means there is less energy for the plant.
Defoliation is also sometimes performed on bonsai in the summer. As Bonsai4me.com explains, "This replacement set of leaves results in increased ramification and leaf density, a reduction in leaf size and internode length and finally, superior Autumn colours." However, defoliation needs to be performed carefully as it may end up harming the tree if it is not strong enough.
