Pests and diseases can damage trees in all stages of development and affect the ability of both natural forests and plantations to meet their management objectives. Some fungi and insects are pests of tree seedlings in nurseries while others attack older trees in a wide variety of ways. While invasive plants compete with seedlings and animals damaging forests are also sometimes problems, the focus here is on insects and diseases. Many examples exist of where one or more species of either indigenous or exotic pests or diseases have caused devastating losses to forests, requiring changes in management regimes or forcing forest managers to switch to alternative tree species. The purpose of this paper is to outline case histories of damaging insects and diseases in forest plantations and to describe the strategies and tactics available to reduce such losses.
