1
point
Black spots

Macadamia    None Given

Older leaves (not all) have black spots up to about 5 feet off the ground. And on a graft the leaves just under new growth. Large new growth 4 limbs about 8 foot up to 9 feet is beautiful. Other newer tree about 13 feet away has no observed spots, it's about 4 foot tall. What are these spots and should I be worried about them?


Posted by: Dale Brown (2 points) Dale Brown
Posted: July 11, 2016


Dr. Ravishankar Narayana commented,
Hi Brown, we can't see the spots properly. Please upload close up image of both surface of leaves. Thanks
over 3 years ago.

Dr. Ravishankar Narayana commented,
Hi, we can't see the spots properly. Please upload close up image of both surface of leaves. Thanks
over 3 years ago.

Dale Brown commented,
Hope these help, Doc.
over 3 years ago.



Answers

0
points
I cannot tell what the problem is. There is surprisingly little detailed information on foliar damage in macadamias.

It is clear that the area surrounding the brown spot has reduced chlorophyll because you can see the halo of yellow. This suggests to me that the spot is caused by a microorganism, likely a fungus. On the other hand it could be that the spot is due to some earlier problem of sun damage or rapid changes in water in the leaf (called oedoma).

The plant can tolerate the damage but the important thing is to establish if the spots are spreading. You have done a good job describing which height and position in relation to the graft. I would make a note of where the spots are and if they begin to spread. If they do it indicates a microorganism and we can then provide further advice.


Posted by: David Hughes (43 points) David Hughes
Posted: July 13, 2016




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