Bacterial Leaf Scorch in Australia

Andrew Mckernan

I have been researching some Plane trees that have scorched margins.

A lot of research in the US point to a Bacterial Leaf Scorch (BLS).

I cannot find any documentation of BLS in Australia. Australian articles indicate that Leaf Scorch is due to root stress. But in the U.S. it seems quite common for Planes and other ornamental shade trees in late summer.

Do we get Bacterial Leaf Scorch in Australia?

One treatment in the US is injections of oxytetracyclene.
My chemical supplier has not heard of it being sold for stem injection here.
Oxytetracyclene is most commonly used for Acne and Chlamydia!
Has any one used this in arboriculture in Australia?

How can I determine if the leaf scorch is bacterial?
In America it seems to be the sole cause of leaf scorch in Planes?


Thanks Andrew

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Eric Frei

Do you have labs to test things down there? Maybe ask the equivalent of the DPI where to get it tested.

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Andrew Mckernan

Ekka, I have not gone down that path as yet.

I have spoken to other arborists, no one has encountered BLS before.
If I can still obtain a reasonable sample then I will seek further testing from department of Ag. in Knox.
The symptoms seem to be a late summer to autumn event. BLS could be overlooked on many site surveys as the trees have just gone through the peak of summer heat and are already headed for dormancy. So brown foliage could be blamed on sun scorch after a hot summer or on early dormancy from drought.

I have photos of the site taken in previous summers that show no signs of leaf scorch. The same drought was in place and the growing environment has not changed. If anything, the only change is the slight easing of the drought. This is consistent with the U.S. studies that show an increase in bacterial development with greater humidity.

I was hoping to find other arborists that have dealt with the same problem here in Australia.
If this is a new problem to our Oak / Maple / Plane tree population then we should get the discussion started. I find it odd that there is so much chatter about BLS in the U.S. but no mention of it here?

I have to admit that prior to this investigation, I thought that scorch was only related to drought or extreme heat exposure. I had never heard of BLS, but it does seem to fit the symptoms that I am looking at.

I would appreciate any references, experiences, general help on the topic of leaf scorch.

Andrew

Eric Frei

I'm in Brisbane so not many deciduous trees here like plane trees.

Not that many fruit trees in suburbia either. We have mango trees and they get hammered with fungal diseases as soon as the weather changes like drought or excess rain.

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