Pest I.D. please

[Raging Bull]

I have a Murraya (mock orange) that has been trouble free for about a year, but has had a developing problem for the last month or so. I'm not sure if it's the water I use for irrigation which is town water, or a pest secreting something on the leaves. All my other plants are unaffected. If you can pick what the problem is please let me know, and what the remedy is.
Thanks in advance, Frank.

[Pearcy001]

Is it mildew? Your tree may not be getting enough airflow. Where is it positioned at the moment? What's your watering like?

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[Raging Bull]

Hi Pearcy,
There's no lack of air movement. It's under shadecloth on my bonsai shelf outside and gets several hours of (shaded) sun a day. It's watered by overhead sprinklers (micro irrigation system) once a day and several short mistings daily, when it's not raining. The white stuff is almost like a little crust and difficult to wipe off, which makes me think it may be an insect secretion of some sort. It doesn't look or feel like mildew.

[AlanBa]

Hi Frank,
It looks like Citrus Psyllids (very similar to what you have there and they attack Murraya).

Alan

[Redsonic]

Hi Frank,
It looks like Citrus Psyllids (very similar to what you have there and they attack Murraya).

Alan

Aren't they supposed to be absent from Australia?

[AlanBa]

I think you are correct there!
But it does look like some sort of Lerp or Psyllid. Are the plants close to or under other trees where the sugar residue and insects can fall or be washed by rain onto them?
We have a yellow box tree which gets Lerps on it and the white sugar flakes with the tiny insects fall over the area under it.
Alan

[Raging Bull]

Thank you all for your help so far. There is nothing above the plant that would fall onto it. As none of my other bonsai around it on the same shelf are affected I'm leaning in the direction of suspecting it's a species (citrus) specific pest. Can anyone suggest a remedy? I would like to get on top of this before it harms the plant.
thank you, Frank.

[melbrackstone]

I have some sort of leaf miner chewing into mine, but it doesn't look like yours. To be honest the patterns on your leaves reminds me of water spots from hard water?

[AlanBa]

A spray with White Oil will get rid of most sucking pests including Scale, Lerps, Psyllids, Aphids, Mites or White Fly.
White Oil should not do any harm, if used to directions and while your daily temperatures are below 30 deg.

Alan

[Raging Bull]

Thanks Alan, I'll try that tomorrow. I'll let you know if it works.
Mel, that's what it looked like to me, but those marks are very difficult to remove, and on the Gold Coast we have very soft water, unlike Adelaide where I've lived for long time before coming here to Qld.
Thank you,
Frank