In the long history of human development, the forest was cut down and serves as an agricultural site for human while its resources is chopped and used as building material. They also hunt for food inside the forest and collect wild fruits and vegetables as their sources of foods. During the increase in population and development of civilization, human clears the forest and used as a site for the agriculture. As the agricultural activities and clearing of the forest had increased, the people become aware that the forest was depleted and soon will be no more natural sources in forest. To overcome this problem, the people come out with a solution which is agroforestry. Agroforestry is a method to combine any agricultural crop or livestock with the forestry plantation as the ecosystem of the forest is kept and balanced. From this solution, timber plantation was emerged as a new agricultural activity and as a new industry in the world.
Acacia mangium is one of the timbers that contributed to the commodities in Malaysia. According to Department of Forestry Peninsular Malaysia (2007 – 2010), the production of log of A. mangium had decreased significantly from 357 m3 to 29 m3. This may because of the increase of other crop plantation and some cases because of the increases of diseases incidence for A. mangium.
2.0 ACACIA MANGIUM DESCRIPTION
Botanical name: Acacia mangium Willd
Synonyms: Mangium montanum, Racosperma mangium,
Mangga hutan, tongke hutan, nak, laj and jerri for Indonesia; black wattle, brown salwood, hickory wattle, mangium and sabah salwood for Australia and England; mangium and kayu SAFODA for Malaysia; arr (Papua New Guinea), maber (Philippines), zamorano (Spain), kra thin tepa and krathin-thepha for Thailand.
2.2 Distribution in Malaysia
A. mangium is a large genus with over 1350 species mostly distributed in the subtropics and the tropics. In Malaysia, its altitudinal range is until 200 m from sea level. In tropical land in Malaysia, mostly A. mangium planted in Sabah and Peninsular Malaysia and now started to increase in Sarawak.
3.0 COMMON DISEASE ON ACACIA
3.1 Heart Rot Diseases
Heart rot diseases had been recognized since the 1980s. It has been identified the diseases caused from hymenomycetes types of fungi. There are several types of fungal infection that causes heart rot diseases but the most common one is Phellinus sp, Tinctoporellus sp. And Rigidoporus sp. This soil borne pathogen usually attacks on the heartwood of the A. mangium. The heart rot happens when the fungi decay in the heartwood.
3.1.1 Symptom and Sign
Usually the fungi can be found behind a yellowish – white or brown, spongy and stringy mass on the heartwood in the stem of A. mangium. The fungi attack only the cellulose and lignin of the woods of the A. mangium. First symptom showed by the infection is discoloration of the heartwood and later will spread to sapwood. In heartwood, there will a pale brown to grey brown color and in sapwood will be tan color to bright yellow in color. In most of the cases, there will be a stem that leaves only the hollow core inside the stem. In Malaysia, there are seven types of heart rot caused by the same fungi which can be distinguished by color, texture and general appearance of the heartwoods after been sawn. These fungi also may found in death wood which may be classified as facultative parasites.
3.1.2 Infection and infestation
These fungi can be transferred by the mechanical equipment, air, and also animal. These fungi cannot attack on the surface of the plant but it must grow inside the plant before it grow and stick on the stem of A. mangium. The fungi can enter the stem during pruning, open wound on the plant, singling and forking injury. The fungi also can affect the young stands and caused death. In Malaysia, the mean incidence range is among 5% until more than 40% of the A. mangium in a timber plantation. These fungi also favors in warm and humid climate.
3.1.3 Economic Importance
Although the heart rot disease does not kill the whole plant but it can decrease the quality of the log wood. The log wood infected by the heart rot disease cannot be used as a construction and building material because of it had decreased its strength. In some plantations that prioritize on the quality for the construction material, it can caused reduction of yield and cause loss to the timber plantation. Most of timber plantation and production uses this infected plant in producing composite material and plywood by integrated to the healthy one and also to the other timber plant species.
3.1.4 Management of Diseases
This disease only can be identified after the stem of plant had been felled. Therefore, some practices may help the timber plantation to decease the infestation of the disease. In some timber plantation, scheduled pruning had been established to reduce the incidence of the disease. The sanitation of the equipment for pruning such as chainsaw must be properly done to avoid the infection of the fungi.
The timber plantation also need to do scheduling and assessment to the A. mangium trees in term of rainfall and climates changes. The properties of the fungi that likes on wet and humid condition allows the timber plantation to do schedule in maintaining the plant such as pruning only be done on except during the rainy season.
3.2 Root Rot Diseases
Root rot disease had cause a serious infection on the A.mangium plantation in Malaysia. Root rot diseases had been identified by several causal of infection especially from various basidiomycete pathogens. The most commons pathogen that causes root rot diseases are soil borne pathogen which are Amauroderma sp. and Ganoderma sp. (red rot diseases), Phellinus noxius and Tinctoporellus epimiltinus (brown rot diseases), Rigidoporus lignosus (white rot diseases), Phytophthora cinnamomi and Pythium vexans. Red rot diseases, brown rot diseases and white rot diseases are the root rot diseases that differ in term of the appearance of the root rot of the plant. These kinds of pathogen also affected the heartwood of A. mangium plant.
3.2.1 Symptom and Sign
The pathogen can be detected by the root appearance based on its color such as red, brown, black or white at the root. Infection by Ganoderma sp. can be identified based on the morphological and the feature of the fruiting bodies of the fungi. The fruiting body can easily locate because it will stay on the stems and appeared roots on the soil surface. Ganoderma philippii and Ganoderma lucidum also can be detected based on its rubbery rhizomorpic skin of the fruiting bodies.
3.2.2 Infection and Infestation
3.2.3 Economic Importance
3.2.4 Management of Diseases
3.3 Phyllode Rust Diseases
3.3.1 Symptom and Sign
3.3.2 Infection and Infestation
3.3.3 Economic Importance
3.3.4 Management of Diseases