Forest health in plantation forests in South-East Asia

In South-East Asia, forest plantations are increasingly important sources of industrial wood for the future, thereby indirectly playing a role in the conservation of natural forest resources. Exotic species are mostly being planted with the expectation of harvest after 15 years or earlier. Their growth rates have generally been encouraging, and some species have performed surprisingly well on poor sites. With the large-scale establishment of these species, several disease problems have emerged, some with the potential to reduce plantation productivity and value of the timber. Eucalypts are the most widely grown exotic plantation species in South-East Asia followed by acacias and teak. The main disease threats to eucalypts are stem cankers and leaf and shoot blight diseases. Acacia auriculiformis and A. mangium are the most popular species of tropical acacias. A phyllode rust. heart rot and root rot are the most serious threats to these plantations. Although a number of diseases have been reported from teak, presently none appear to be particularly threatening. The most significant disease of tropical pines is a needle blight whereas a blister bark disease is the most serious threat to the two main species of casuarinas grown in South-East Asia, i.e. C. equisetifolia and C, junghuhniana. Paraserianthes falcataria, a fast-growing legume is also popular but the success of these these plantations may be limited by pink disease and a gall rust. Options for management of these disease threats are discussed.