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Virus Diseases In Agriculture, George Mclean

Journal of the Department of Agriculture, Western Australia, Series 4

Viruses are extremely small particles which can only be seen with an electron microscope. A virus is present in a diseased plant as huge numbers of tiny particles within the cells of the plant. Viruses which are infectious can cause disease, and reproduce only inside the cells of a living plant.

Many insects transmit plant virus diseases—aphids, leafhoppers, mealy bugs, thrips and beetles. Generally a virus is spread by only one of these groups of insects.

The Western Australian Department of Agriculture is expanding the diagnostic service for the identification of plant viruses.

Decide : How Much Superphosphate, G A. Robertson, J. W. Bowden, N. J. Halse

Journal of the Department of Agriculture, Western Australia, Series 4

* A 400 per cent increase in ihe price of superphosphate has reduced the economic optimum rates of super for crops and pastures in 1975.

* Many factors, both biological and economic, must be taken into account in determining the rate of superphosphate to apply.

• DECIDE, a model developed by CSIRO and the Department of Agriculture, provides a formal system in which all these factors can be considered.

• DECIDE is based on the results of all research on superphosphate carried out in Western Australia. However, each farmer's own knowledge of his farm, the soils, crops and animals is …