Fungi associated with heart rot of Acacia mangium in peninsular Malaysia.

By S.S. Lee and Maziah Zakaria

 

There are seven main types of rot encompasses honeycomb rot, spongy and spongy rot with zone lines, wet and white fibrous rot, brittle rot and also pink pocket rot. These seven main types of rot can be distinguished by macroscopic observations including its color, texture and general appearances. This article shows that white fibrous rot often found. Whereas only few of pink pocket rot are being found. Rotted wood of A. mangium mostly cause by Hymenomycetes that attack cellulose and lignin of plant resulting whitish spongy product. A total 41 Hymenomycetes isolates from rotted trees varying ages between one and eight years of A. mangium. After a certain time, 41 Hymenomycetes reduce to 25 different fungi.  Each assigned with a code and observation shows that white fibrous rot invade trees at all ages. Fungal fruiting bodies were found on only two occasions, which is from a branch of a 2 years old tree from Bukit Tarik and from the stem of a 1 year old tree also from Bukit Tarik. The fruiting bodies which from the branch of the tree identified as a Tremetes sp. While the one from the stem of the tree is identified as Fomes sp. Both these fungi were found on tress which had white fibrous heart rot. No one fungus was consistently isolated from the many samples of rotted or decaying heartwood of A. mangium trees younger than 7 years old although P. noxius was consistently isolated from 7 and 8 years old trees from various locations. The overall diversity of fungi isolated from samples obtained from the different sites indicates a diversity of inoculum in each site. It has been observe that there remains large amounts of woody debris in the form of old stumps and logs, fallen trees and branches which often bear fruiting bodies of various saprophytic wood decay fungi. Based on the scientist hypothesis fungi which normally grow on the dead wood in the plantation are also able to invade the essential dead heartwood of the living trees through dead branch stubs and wound which expos the heartwood of the tree and then cause decay. The best strategy to control the disease would be to breed trees that are less branchy and that heal rapidly upon wounding. Another alternative would be to ensure complete removal of woody debris from the area to be planted so as to eliminate the occurrence of the potential inoculum sources later on.