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<pre>Unless you are 100% sure that the cause of the leaf yellowing is that
beetle then the application of 'an insecticide' through the irrigation
system seems a bit heavy handed. What are the ramifications of this
insecticide, will it kill all living things in the soil? Including those
that are desirable?

There are other ways of dealing with soil borne pests using
biopesticides such as developed by the CSIRO on the following;

http://www.researchresults.csiro.au/rr5/rr5a04.html

Roger Farquhar Hunter Valley

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