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 124<br />
and as a special treatment against the decay organisms<br />
and pests which grow and breed in the slash (Bagchee<br />
1954).<br />
The infestation by mistletoes can be controlled by<br />
lopping be<strong>for</strong>e the ripening <strong>of</strong> the fruits and their<br />
dispersion by birds (De 1945).<br />
The service life <strong>of</strong> treated wood has been estimated<br />
to be six times more than that <strong>of</strong> untreated wood. Greater<br />
utilisation <strong>of</strong> preservative treated wood would lessen the<br />
demand <strong>for</strong> timbers. An efficient conservation<br />
programme could there<strong>for</strong>e be implemented (Hong and<br />
Daljeet-Singh 1985).<br />
<strong>Research</strong> Priorities<br />
Pest and disease problems are going to play an important<br />
role in enrichment planting and establishment <strong>of</strong> <strong>for</strong>est<br />
plantations. As <strong>for</strong>est exploitation continues, the natural<br />
balance <strong>of</strong> pest and diseases in the <strong>for</strong>est ecosystem will<br />
be disturbed. Pathogens and pests are likely to play an<br />
important role in a wide variety <strong>of</strong> ecological and<br />
evolutionary phenomena. There is a need to <strong>for</strong>mulate a<br />
good pests and diseases management programme, both<br />
at national and regional levels, with identification <strong>of</strong><br />
priorities and to support the development <strong>of</strong> technology<br />
and capacity to face pests and diseases. <strong>Forestry</strong> pests<br />
and diseases on <strong>dipterocarps</strong> occur in six major<br />
categories: seed storage, nursery problems,<br />
establishment problems, chronic and sporadic problems,<br />
wood destruction and fruiting and seedling survival in<br />
natural stands.<br />
The main constraints on dipterocarp pest and disease<br />
research are shortage <strong>of</strong> trained staff, lack <strong>of</strong> cooperation<br />
among scientists and institutions working on pests and<br />
diseases in Asia, inadequate funding and infrastructure<br />
facilities, high cost <strong>of</strong> pest and disease identification,<br />
lack <strong>of</strong> in<strong>for</strong>mation on the economic effects <strong>of</strong> pests in<br />
plantation <strong>for</strong>estry, and the need <strong>for</strong> more contacts<br />
between researchers, <strong>for</strong>esters and staff <strong>of</strong> timber<br />
companies.<br />
Future research should there<strong>for</strong>e include the following<br />
aspects:<br />
1. Seed destruction and fungal infection during storage<br />
Although the main insect predators and pathogenic<br />
fungi have been identified, emphasis is needed on<br />
controls, their application, effectiveness and impact<br />
on seed germination and seedling development.<br />
Chemicals as well as biological controls should be<br />
tested.<br />
2. Pest and diseases in nursery<br />
Except <strong>for</strong> major epidemics, attacks and infections<br />
can be managed by chemicals and cultural practices.<br />
Nevertheless, control methods need more systematic<br />
study. Biological control can also be considered as a<br />
preventive method: soil-borne fungi such as<br />
Trichoderma and Gliocladium species can be used<br />
as antagonists to soil-borne pathogens and cultured<br />
in the seedling beds.<br />
3. Pest and diseases during establishment <strong>of</strong> seedlings<br />
and saplings in plantations and exploited <strong>for</strong>ests<br />
Since enrichment planting and <strong>for</strong>est plantation<br />
involve investment, failure <strong>of</strong> establishment can be<br />
economically devastating. Special attention has to be<br />
given to pests and diseases <strong>of</strong> dipterocarp seedlings<br />
and saplings. Shoot destruction can become a serious<br />
problem <strong>for</strong> <strong>for</strong>est management as it induces the<br />
<strong>for</strong>mation <strong>of</strong> lateral and multiple leaders. Chemical<br />
control is not practicable in large <strong>for</strong>est areas and<br />
other methods need investigation. Prevention can also<br />
be assisted by dipterocarp species mixture and<br />
diversity.<br />
4. Defoliation and heart-rot problems<br />
Damage assessment systems <strong>for</strong> defoliation and<br />
heart-rot and their economic impacts are required,<br />
as well as the study <strong>of</strong> biology and ecology <strong>of</strong> the<br />
pests and pathogens. Pathogens have a major<br />
influence over <strong>for</strong>est re<strong>for</strong>estation methods and<br />
breeding programmes (Augspurger 1990). Chronic<br />
and sporadic pest and disease problems need to be<br />
more systematically studied and their economic<br />
losses fully quantified.<br />
5. Fruit and seedling pest and diseases<br />
More studies on pests and diseases related to fruiting<br />
and seedling survival should be conducted to better<br />
understand fruiting and dispersal strategies, seedling<br />
survival, management and selection <strong>of</strong> the mother<br />
trees, and ability to resist pathogens and pests.<br />
6. Insect and fungal population<br />
Studies on insect and fungal population ecology and<br />
dynamics are also essential <strong>for</strong> the conception <strong>of</strong> a<br />
good pest and disease management programme as<br />
well as a search <strong>for</strong> resistant individuals (mothertrees).<br />
7. Revision <strong>of</strong> the insect taxonomy<br />
The long lists <strong>of</strong> identified insect pests in literature