Dieback is a disease of trees and shrubs. Dieback results in the death of young shoots and spreads over time form the growing tips toward the larger branches. Several factors can cause dieback, including drought, damage to roots, infection by fungus, defoliation (loss of leaves) by leaf-eating insects, and rising levels of soil salinity (saltiness). Dieback has affected many millions of acres or hectares of tree-studded farmland and open forest in Australia.