A review of dipterocarps - Center for International Forestry Research

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