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
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Pests and Diseases <strong>of</strong> Dipterocarpaceae 121<br />
1961, Elouard unpublished). Schyzophyllum commune<br />
has been reported as causing die-back <strong>of</strong> young saplings<br />
<strong>of</strong> Shorea robusta, cankers caused by frost or fire<br />
providing the route <strong>of</strong> entry. The fungus, once established,<br />
attacks the living sapwood killing the stem beyond the<br />
scars, and it progresses both up and down the stem<br />
(Bagchee 1954).<br />
Various fungi cause leaf diseases, an infection <strong>of</strong><br />
leaves characterised by spots, necrosis and leaf fall<br />
(Hawksworth et al. 1983), and most <strong>of</strong> them belonging<br />
to Imperfect Fungi (Deuteromycetes). In most cases,<br />
growth <strong>of</strong> seedlings and saplings is not affected, except<br />
when large spot areas (dead and necrosed cells)<br />
significantly reduce the leaf area <strong>for</strong> photosynthesis. The<br />
weakened plant becomes more susceptible to pathogen<br />
and pest attacks, or is less competitive with other<br />
seedlings and saplings in natural stands. Ultimately, the<br />
leaf becomes completely necrosed and dry and falls. On<br />
seedlings and young saplings, the defoliation can<br />
eventually lead to death (Hong 1976, Mridha et al. 1984,<br />
Charlempongse 1988, Harsh et al. 1989, Elouard l99l,<br />
Zakaria personal communication, Elouard unpublished).<br />
Some fungi, such as Meliola sp. develop a dense dark<br />
mat on the leaf surface, sometimes entirely covering the<br />
leaf area. Though the hyphae do not penetrate the leaf<br />
cells, chlorophyll development is hindered (Elouard<br />
l991). An alga, Cephaleuros virescens<br />
(Trentepholiaceae), was also recorded causing leaf<br />
disease on seedlings and saplings in India, Indonesia and<br />
Malaysia and on trees in India (Mittal and Sharma 1980,<br />
Elouard 1991).<br />
Thread blights recorded on <strong>dipterocarps</strong> are caused<br />
by Basidiomyceteae <strong>of</strong> the genera Marasmius and<br />
Corticium. There are two kinds <strong>of</strong> thread blights, white<br />
and dark. The white thread blights are produced by the<br />
development <strong>of</strong> whitish mycelium sticking on the twigs,<br />
branches and foliar system <strong>of</strong> the seedlings and saplings.<br />
The black thread blights are horse hair-like and attached<br />
to the host by byssus. The threads do not stick to the<br />
host’s organs except by the byssus, but develop an aerial<br />
network which, when too excessive, can hinder the host’s<br />
development. These fungi were observed in plantation<br />
and natural <strong>for</strong>ests in India, Indonesia and Malaysia<br />
(Symington 1943, Bagchee 1953, Bagchee and Singh<br />
1954, Spaulding 1961, Smits et al. 1991, Elouard 1991,<br />
Elouard unpublished).<br />
Gall <strong>for</strong>mation on shoots <strong>of</strong> seedlings and saplings<br />
has been described in Shorea javanica plantations in Java<br />
(about 60% <strong>of</strong> the seedlings affected), man-made<br />
dipterocarp <strong>for</strong>ests <strong>of</strong> Sumatra and on Shorea spp. and<br />
Upuna borneensis (100% <strong>of</strong> the plants affected in<br />
nursery) in Kalimantan (Ardikoesoema 1954, Torquebiau<br />
1984, Smits et al. 1991). This gall <strong>for</strong>mation is<br />
commonly attributed to a bacterium, Agrobacterium<br />
tumefaciens. According to Smits et al. (1991), the<br />
youngest leaf remains smaller than the leaves developed<br />
be<strong>for</strong>e infection, subsequent leaves no longer develop<br />
from the top shoot and all buds in the zone with green<br />
leaves produce side buds. This process continues until a<br />
dense clump <strong>of</strong> tiny shoots is produced at the buds’<br />
positions but without development <strong>of</strong> any normal shoots<br />
from these clumps. The plant growth is then stopped. An<br />
insect is suspected to be the vector <strong>for</strong> this bacteria<br />
(Torquebiau 1984, Smits et al. l991).<br />
Trees<br />
About 150 fungal species have been recorded on trees,<br />
mainly causing rots and decay. In addition, leaf damage,<br />
flower necrosis and cankers were also reported.<br />
Parasitic plants <strong>of</strong> the family Loranthaceae have severely<br />
damaged Shorea robusta in India.<br />
Leaf disease on trees is harmful if the damaged area<br />
covers a large area <strong>of</strong> the foliar system. The fungal leaf<br />
diseases are mainly caused by species <strong>of</strong> Asterina,<br />
Capnodium, Cercospora, Colletotrichum<br />
(Thirumalachar and Chupp 1948, Bagchee 1953, Bagchee<br />
and Singh 1954, Chaves-Batista et al. 1960, Spaulding<br />
1961, Bakshi et al. 1967-1972, Elouard 1991).<br />
Cankers and rots were recorded on various<br />
dipterocarp species in Peninsular Malaysia, Thailand,<br />
Singapore, Indonesia and India (Bagchee 1954, 1961,<br />
Bagchee and Singh 1954, Bakshi 1957, 1959, Bakshi et<br />
al. 1967, Panichapol 1968, Hong 1976, Charlempongse<br />
1985, Kamnerdratana et al. 1987, Corner 1987, l991,<br />
Elouard 1991).<br />
Few fungal species are able to attack healthy trees.<br />
Aurificaria [Polyporus] shoreae, a fungus only reported<br />
on Shorea robusta, is capable <strong>of</strong> infecting healthy and<br />
uninjured roots, causing root rot and bark and sapwood<br />
decay. The disease results in top die back and death <strong>of</strong><br />
trees (Bakshi and Boyce 1959). Most <strong>of</strong> fungal species<br />
are secondary parasites infecting the trees through<br />
wounds and are distinguished from the primary parasites<br />
which produce active root and stem rot. According to<br />
Bagchee (1954), at least 24 species <strong>of</strong> Hymenomycetes<br />
behave as facultative parasites <strong>of</strong> Shorea robusta.