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Wednesday, 22 March 1972
Page: 789


Senator MULVIHILL asked the Minis ter representingthe Minister for the Interior, upon notice:

(1)   In view of 'the answer given to Senate Question No. 1714 that the spread of root rot due to Phytophthora cinnamoni has reached the Australian Capital Territory is the Minister able to confirm if this disease has spread beyond Eucalypt forest and is affecting trees within the suburbs of Canberra; if so could trees in Dampier Crescent. Forrest be affected.

(2)   Has this disease caused affected trees in streets to lose their leaves and branches to die; if so, does the Minister regard the disease as an immediate threat to Canberra's environment.

(3)   What action, if any, is being taken to save the trees in, the streets of Canberra that are threatened by this disease.


Senator COTTON - The Minister for the Interior has provided the following answer to the honourable senator's question:

(I)   It has been known for several years that Phytophthora cinnamoni has been present in soils of the Australian Capital Territory both within the city and in the natural forests. It has probably been present without positive identification for many years earlier but only becomes evident when plants are subjected to physiological stress through poor drainage of wet conditions and alternative drought.

The most significant damage which has been identified with Phytophthora by Parks and Gardens Branch of the Department of the Interior has occurredin the Botanic Gardens and Commonwealth Gardens but numerous positive identification tests have resulted from samples taken after deaths of trees and shrubs both in public parks and private gardens. However in all cases the advent of the disease as occurred in badly drained sites m heavy clay soils. The trees in Dampier Crescent have been examined and are free from presence of Phytophthora. They have been severely affected by Lerps during the past summer but this is not likely to have any lasting effect.

(2)   Dropping of leaves is not a symptom of the disease; rather does the plant die from lack of ability to absorb water following the death of the root system after infection from the soil-borne fungus. The tree or plant is likely to die as a whole and retain the dead leaves. Occasionally visible damage may start with the death of a major branch if it arises near the base of the plant.

Because of the sporadic effect of incidence of the disease and its association only with poor drainage it is not regarded as likely to provide a major threat to Canberra's environment.

(3)   The incidence on street trees in Canberra is negligible. Where positive identification is obtained after the death of a tree it is not customary to plant another tree in the same position but to replace the tree clear of the infected site making sure that good drainage is provided.

A post graduate research student of the ANU is currently undertaking investigation of the occurrence and control of Phytophthora cinnamoni in the Botanic Gardens and Black Mountain on behalf of the Department of the Interior.

Prevention of the spread of the disease is being minimised by exercising extreme nursery hygiene care in growing plants and sterilising any infected area where shrubs or trees must be replanted. The most important prevention measure however is to ensure that the site is correctly drained when planting shrubs or trees in a new garden or park.







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