A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
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Pests and Diseases <strong>of</strong> Dipterocarpaceae 122<br />
Infection by heart-rot fungi on hardwood trees occurs<br />
through initial injuries caused by human activities (e.g.<br />
tapping), fire, drought, frost and other mechanical causes.<br />
These fungi establish themselves when the trees are<br />
either young or overmature. Most <strong>of</strong> these fungi live as<br />
saprophytes in jungle slash and become parasites when<br />
conditions <strong>for</strong> infection are favourable (Bagchee 1954).<br />
Trees with heart-rot can exhibit all the outward signs <strong>of</strong><br />
healthy and vigorous growth. Heartwood is progressively<br />
decayed with age. Heart-rot in Shorea robusta can cause<br />
much loss <strong>of</strong> timber (e.g., 9-13%, with nearly 73% <strong>of</strong><br />
the trees infected) (Bakshi et al. 1967). Bagchee (1954)<br />
reported that nearly 80% <strong>of</strong> trees with de<strong>for</strong>mities have<br />
fungus-rot in their stems. Of Shorea javanica trees<br />
tapped <strong>for</strong> resin in Sumatra, 10% showed carpophore<br />
development on their trunks, indicating advanced<br />
infection (Elouard 1991). The fungi entering through the<br />
butt-scars and causing root damage contribute to<br />
windthrown trees (Bakshi and Boyce 1959). Infection<br />
by rot fungi is more frequent in the suppressed trees in<br />
overcrowded <strong>for</strong>ests than in the trees <strong>of</strong> thinned coupes<br />
(Bagchee 1954).<br />
Flower destruction and seed abortion may be a<br />
serious problem <strong>for</strong> seed production under <strong>for</strong>est<br />
management. However, there has been little research, and<br />
the only record is Curvularia harveyi on Shorea<br />
pinanga in Indonesia (Elouard 1991).<br />
Parasitic plants, belonging to Loranthaceae, were<br />
observed on Shorea robusta in India and Bangladesh<br />
(Davidson 1945, Singh 1954, Ghosh 1968, Alam 1984)<br />
and on S. obtusa in Thailand (Charlempongse 1985). The<br />
parasites caused serious damage although the trees did<br />
not die (Davidson 1945, Alam 1984). The trees tended<br />
to <strong>for</strong>m epicormic branching in some <strong>of</strong> the older<br />
plantations. The only method <strong>of</strong> controlling infestations<br />
<strong>of</strong> Loranthus appears to be eradication by lopping in the<br />
cold weather (De 1945).<br />
Forest Products<br />
Diseases on <strong>for</strong>est products are primarily wood decay<br />
and staining fungi (Bagchee and Singh 1954, Banerjee<br />
and Sinhar 1954, Sivanesan and Holliday 1972, Hong<br />
1980a, b, Shaw 1984, Balasundaran and Gnanaharan 1986,<br />
Supriana and Natawiria 1987, Kamnerdratana et al.<br />
1987). Most <strong>of</strong> them belong to the Basidiomyceteae and<br />
can be categorised as white rot, brown rot and s<strong>of</strong>t rot.<br />
In white rot, both lignin and cellulose are attacked. In<br />
brown rot, cellulose and hemicellulose are attacked while<br />
lignin remains unaffected. In s<strong>of</strong>t rot, cellulose is<br />
removed like brown rot but the mechanism <strong>of</strong> action on<br />
cell walls is different. The fungi causing s<strong>of</strong>t rot belong<br />
to Ascomycetes and Fungi Imperfecti and are restricted<br />
to hardwoods (Supriana and Natawiria 1987). Decay <strong>of</strong><br />
timber occurs mostly after felling, on wood in service<br />
and on industrial wood products. Likewise, on logs and<br />
poles an important number <strong>of</strong> wood decay fungi have been<br />
identified and control methods investigated. Most <strong>of</strong><br />
these fungi are weak pathogens, though some can also<br />
infect living trees, e.g., Hypoxylon mediterraneum<br />
recorded both on trees and wood attacking Shorea<br />
robusta trees and hastening their death or preventing<br />
recovery (Boyce and Bakshi 1959).<br />
Decay fungi affect boats (Premrasmee 1956, Savory<br />
and Eaves 1965) and wall framing (Singh 1986). One <strong>of</strong><br />
the most common decay fungi is Schyzophyllum<br />
commune recorded in India, Indonesia, Thailand and<br />
Philippines (Bakshi 1953, Bagchee and Singh 1954,<br />
Mizumoto 1964, Supriana and Natawiria 1987,<br />
Charlempongse 1985, Quiniones and Zamora 1987).<br />
Various dipterocarp species, Shorea elliptica, S.<br />
hypoleuca and S. laevis are highly resistant to<br />
Chaetomium globosum (s<strong>of</strong>t rot) and Trametes<br />
[Coriolus] versicolor (Takakashi and Kishima 1973) and<br />
Shorea siamensis is extremely durable against<br />
Coniophora cerebella, Trametes [Polystictus]<br />
versicolor and Daedalea quercina (Bavendam and<br />
Anuwongse 1967). Shorea guiso, Hopea parviflora and<br />
Vateria indica proved to be resistant to several fungal<br />
species (Moses 1955, Balasundaran and Gnanaharan<br />
1986). Veneer-faced, low-density particleboards<br />
including Shorea particles, tested <strong>for</strong> its resistance<br />
against Tyromyces palustris and T. versicolor proved to<br />
be resistant (Rowell et al. 1989).<br />
Treatments, heating, fumigants, Wolman salt, ascu and<br />
borax, boliden K-33 and tanalith C. were tested on various<br />
wood species against decay fungi. Copper-chromearsenic<br />
(CCA) is the most widely used preservative in<br />
Malaysia <strong>for</strong> wood protection, but organotins are better<br />
since they have a higher fungicidal activity, provide a<br />
higher protection against the marine toredo worm, are<br />
less toxic towards mammals and more easily degradable<br />
(Hong and Khoo 1981, Hong and Daljeet-Singh 1985).<br />
Wood staining fungi infect logs in logging areas and<br />
freshly sawn timbers in saw mills. A large amount <strong>of</strong><br />
money is spent each year on preservatives to overcome<br />
this problem <strong>of</strong> staining (Hong 1981b). The staining does