Defoliation

noun

1. Loss of leaves, as by the depredations of insects; specifically, the fall of leaves in autumn.
2. The separation of ripened leaves from a branch or stem; the falling or shedding of the leaves.
3. the act or process of causing plants to lose their leaves, especially by application of a chemical agent.
4. The separation of ripened leaves from a branch or stem; the falling or shedding of the leaves.
5. causing the leaves of trees and other plants to fall off (as by the use of chemicals)