||Technology in Australia 1788-1988
Table of Contents
I Management Of Native Forests
II Plantations-high Productivity Resources
III Protecting The Resource
i From fire
ii From biological attack
IV Harvesting The Resource
V Solid Wood And Its Processing
VI Minor Forest Products
VII Reconstituted Wood Products
VIII Pulp And Paper
IX Export Woodchips
X Future Directions
From biological attack (continued)In 1951 Australia's whole softwood plantation program was thought to be threatened when the wood wasp, Sirex noctilio, was discovered in Melbourne in a shipment of wood from overseas. The wasp, a native of the northern hemisphere, had already been introduced to New Zealand, where it had caused damage to pine plantations. Although strict quarantine measures were taken, by 1961 the wasp was found to be infecting radiata pine stands close to Melbourne. (The wasp had also been found in a small radiata pine plantation close to Hobart in the early 1950s, but appeared not to have spread from there.) Over the next few years it was apparent that Sirex was spreading to the north and east of Melbourne and the threat had become sufficiently great for the Commonwealth and State Governments, together with private industry, to set up a National Sirex Fund for research and eradication. The problem was first tackled by identification and removal of affected trees but by the late 1960s research by CSIRO, together with the Forests Commissions of Victoria and Tasmania had indicated that biological control with other wasps parasitic on Sirex was feasible. This was introduced in both Victoria and Tasmania, using a number of species (Ibalia, Rhyssa, Megarhyssa and Schletterius) which oviposited in Sirex eggs and larvae. In the early 1970s, following further CSIRO research by Bedding and Akhurst, a different approach was introduced which involved infecting the female Sirex with a parasitic nematode (Deladenus siricidicola) which renders it sterile. Logs inoculated with the nematode were originally distributed in plantations to spread it amongst the Sirex population but a later technique involved killing 'trap' trees with a weedicide, said to make them more attractive to Sirex, and inoculating them with the nematode. The use of Deladenus siricidicola has been more effective than the use of parasitic wasps and while Sirex is still slowly spreading out of Victoria into South Australia, NSW and ACT it is no longer regarded as a serious threat to plantations which are thinned correctly to eliminate the occurrence of suppressed or unhealthy trees.
The exotic pine plantations have also been subject to other pests and diseases but none has caused the same concern as Sirex. Diseases caused by the fungi Dothistroma, which has been severe in New Zealand, and Diplodia have occurred sporadically. Outbreaks of the former in north-eastern Victoria and some areas of NSW have been controlled by aerial application of fungicide.
Organisations in Australian Science at Work - CSIRO Division of Entomology; Forestry and Timber Bureau; Forests Commission of Victoria; National Sirex Fund; Tasmania. Forestry Commission
People in Bright Sparcs - Akhurst, R. J.; Bedding, R. A.; Zentmyer, G. A.
© 1988 Print Edition pages 211 - 212, Online Edition 2000
Published by Australian Science and Technology Heritage Centre, using the Web Academic Resource Publisher