The first sign you will see is a dead or dying patch of your murraya in an otherwise healthy green tree / shrub. You may see a neat little pile of shavings on the garden bed, if the wind and rain has not disturbed them. On closer inspection, you will likely find the dead limb hanging on by a whisper, or broken off and still within the hedge. If the woody end of the dead limb looks hollowed out as per the picture, then your detective work need go no further.
Treatment
Firstly, completely remove any dead sections from your garden completely to help minimise re-infestation. If possible, cut off the bored section of the remaining plant. If this is not viable, a pesticide is the next step.
There are two approaches to this pesticide application
- Spray of the tree / hedge with a product like Confidor / Pest Oil.
- Apply via a root drench of the same product to the tree / hedge, or the slow release tablets (Confidor).
Both methods are aiming at getting the pesticide inside of the plant, so that when the borers eat it, they die. Depending on your prevailing weather conditions, pick the method that will suit you best. When it is dry, the pesticide will readily be absorbed into the plant through the leaves, but would be less effectively taken up through the roots in tablet form - in dry ground. However if you are experiencing rainy spells, the root drench or tablet form is likely to be more effective than product sprayed on the leaves.
The last picture in the gallery above shows a shaped murraya bush that is recovering after a severe citrus borer attack. There is hope, these tough specimens do bounce back. If they have had an attack though, do give them a little extra care to speed their recovery with some fertiliser and water. Do be careful not to overdo the water though during treatment stages if using uptake methods through roots/root drench.
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