PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Dothistroma control
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See also needle diseases of radiata pine
Dothistroma control
From Forest Health News 159, February 2006
The needle-cast fungus Dothistroma has been present in New
Zealand plantation forests for over 40 years. Since the mid 1960s
there has been considerable research directed at developing
suitable methods for managing the disease and, as a result of this
work, there has been an annual aerial spray programme to control
infection in plantations.
While most of the research has been carried out by the Forest
Research Institute (under its various titles), the control programme
has been the responsibility of the Dothistroma Control Committee
(DCC). In the early days the Forest Service was responsible for
the work of the DCC; today it is a sub-committee of the New
Zealand Forest Owners’ Association.
Dothistroma is a disease that infects the needles of pines and causes
early needle death. As infection levels get higher (15–25%) some
loss of growth begins to occur and in severe cases growth stops.
The disease rarely kills trees but does cause a significant reduction
in growth if left unchecked at high infection levels.
Aerial spraying has been refined as a management tool to
complement other control initiatives for the disease. A tree
breeding programme has been going for many years allowing
forest owners to plant resistant breeds on susceptible sites. This,
combined with timely thinning and pruning (to improve airflow
through the stand), can reduce the rate and severity of infection.
However, these tools are sometimes not enough and managers
need to spray their trees with a copper fungicide to reduce infection
levels and keep their stands healthy and growing. In order to ensure
a cost effective programme is developed for all forest owners, the
DCC coordinates the purchase of the copper fungicide and oil
used for spraying and the application of the spray. There is mutual
benefit here because fungi do not respect ownership boundaries
and neighbourly relations are enhanced if everyone with severe
Dothistroma does control spraying.
The DCC also invests in ongoing research to improve the spray
used, to find improved application techniques and to ensure that
the operation is sustainable, and to mitigate any adverse
environmental effects.
The DCC continues to work closely with Ensis (FRI) to ensure
the best information is available to forest owners and the disease
can be managed as cost effectively as possible.
Forest owners are urged to get their forests surveyed in July/August
and to contact the DCC as early as possible after the survey to
ensure their forests are treated in a timely manner. Spraying usually
occurs between Labour Weekend and Christmas, and if required
a second application (for severely infected stands) is carried out
in February.
The DCC can be contacted on 07 3323 454 or 0274 885 940.
(Don Hammond, Secretary, DCC)
