What’s attacking our Acers’ leaves?
Discussion
We have two ornamental standard Acers, which always seem to suffer leaf damage each year resulting in holes that expand into extensive leaf damage as the year progresses.
They have come into leaf in the last week or two, so there are no holes yet. But I’ve noticed what might be the culprit: small reddish, raised nodules on the upper surface of some of the leaves. They are pinhead size.
What do you think these are? Fungal, or insect? Some sort of scale insect perhaps?
I’ve given them a spray of RoseClear fungicide for now, and will give them a spray of BugClear Ultra in a day or two. Will either of those work?

They have come into leaf in the last week or two, so there are no holes yet. But I’ve noticed what might be the culprit: small reddish, raised nodules on the upper surface of some of the leaves. They are pinhead size.
What do you think these are? Fungal, or insect? Some sort of scale insect perhaps?
I’ve given them a spray of RoseClear fungicide for now, and will give them a spray of BugClear Ultra in a day or two. Will either of those work?
Edited by Dr Mike Oxgreen on Tuesday 22 April 10:19
Magic indeed! Thanks!
I’m still not yet in the habit of thinking of AI.
It does look like a distinct possibility. Sadly, I’ve just read that spray is unlikely to be effective once the mites are enclosed by the galls. But I’ll spray periodically anyway, and I’m guessing the BugClear is the one to use.
And it seems that you need to spray very early before the leaves are fully unfurled, and including the bark where the mites overwinter.
In the olden days I’d have used a systemic insecticide. Do any of those still exist?
I’m still not yet in the habit of thinking of AI.
It does look like a distinct possibility. Sadly, I’ve just read that spray is unlikely to be effective once the mites are enclosed by the galls. But I’ll spray periodically anyway, and I’m guessing the BugClear is the one to use.
And it seems that you need to spray very early before the leaves are fully unfurled, and including the bark where the mites overwinter.
In the olden days I’d have used a systemic insecticide. Do any of those still exist?
Dr Mike Oxgreen said:
In the olden days I’d have used a systemic insecticide. Do any of those still exist?
BugClear is both contact & systemic, can't remember the other one I use alongside it but that's similar too.In my experience it definitely works systemically due to the duration of effectiveness after spraying.
JoshSm said:
BugClear is both contact & systemic, can't remember the other one I use alongside it but that's similar too.
In my experience it definitely works systemically due to the duration of effectiveness after spraying.
Ah great, yes.In my experience it definitely works systemically due to the duration of effectiveness after spraying.
I’ve just checked and it does indeed claim a degree of systemic action. So too does the Provanto Ultimate Bug Killer, of which I’ve got a couple more spray bottles.
Dr Mike Oxgreen said:
JoshSm said:
BugClear is both contact & systemic, can't remember the other one I use alongside it but that's similar too.
In my experience it definitely works systemically due to the duration of effectiveness after spraying.
Ah great, yes.In my experience it definitely works systemically due to the duration of effectiveness after spraying.
I’ve just checked and it does indeed claim a degree of systemic action. So too does the Provanto Ultimate Bug Killer, of which I’ve got a couple more spray bottles.
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