Fungal diseases in planted forests

Plantations of exotic, fast growing forest tree species are increasingly being established in South East Asia. While there may be adequate information on the silviculture and management of some of these species, little is known about their pests and diseases, especially under large-scale plantation conditions. This paper discusses some of the more important and damaging fungal diseases, the associated pathogens and methods of control of some of the more popular planatation tree species being planted in this part of the world. Among nursery disease, the most important disease is damping-off which affects a very wide range of hosts, both in agriculture and forestry. Web-blight caused by Rhizoctonia solani is another important nursery disease. Other diseases which may cause significant damage in the nursery are powdery mildews and leaf spots. Root rot diseases have been identified as a major potential problem in forest plantation, especially where plantations have been established on logged over forest sites. A host of fungi are associated with rot disease and their control is highly dependent on careful land preparation and sound management. Stem cankers are another disease viewed with concern in fast growing forest plantations but this disease require more detailed studies. pink disease cause by Corticum salmonicolor has been recorded on a wide range of perennial hosts in the tropics including several fast-growing timber tree species. Its long recognition as a disease are importance in rubber plantations has resulted in the formulation of effective control methods. Heart rot, which is normally a defect of old and overmature trees have been found in fast-growing plantations trees such as Acacia mangium and Eucalyptus geglupta. Its control however, is difficult as the associated fungi enter the living tissues through branch stubs, broken brances and wounds. Leaf spot diseases are common both on seedings in the nursery and on trees in the fiels and may produce minor or severe symptoms depending on the host and the casual organism. For reasons of economics and logistics, chemical control is most effective and efficient in the nursery. Rust disease have been record on several forest plantation tree species. On PAraserianthes falcataria, damage has been severe with high mortality, and on Tectona grandis serious loss in increment has been recorded. While a large number of rust fungi have been recorded on the acacis, and the observation of a high incidence of gall rust on. A mangium is worrying, their impact on the crop is still unknown.