Japanese maple leaves turning black

[Japonicus]

I sprayed this Katsura a week or so ago with copper. Will repeat tomorrow and add Infuse granules.
Verticilliam wilt? Tree is planted in ground for bonsai not mulched.

 

[Firstflush]

Did it happen after the copper treatment?

 

[Japonicus]

Did it happen after the copper treatment?

Yes. All trees got the treatment, this is the only one with a problem so far.

 

[Firstflush]

I’m not a JM expert by any means, but it appears to me to be chemical burn. Katsura is one of the more delicate maples, right? Your mix could have too concentrated for that particular tree. Also, if you sprayed during the day with the sun out, it could of exacerbated the situation.

General horticultural best practices indicate spraying should be done in the morning or evening to avoid full sun on the leaves in addition to presence of pesticides, fungicides etc...(even with inert organic sprays)......many would disagree.

In my experience, spraying out of direct sun is most important with soaps and horticultural oils.

 

[Japonicus]

I’m not a JM expert by any means, but it appears to me to be chemical burn. Katsura is one of the more delicate maples, right? Your mix could have too concentrated for that particular tree. Also, if you sprayed during the day with the sun out, it could of exacerbated the situation.

General horticultural best practices indicate spraying should be done in the morning or evening to avoid full sun on the leaves in addition to presence of pesticides, fungicides etc...(even with inert organic sprays)......many would disagree.

In my experience, spraying out of direct sun is most important with soaps and horticultural oils.

All my trees got the spray. The Katsura in ground is the one I cut these leaves from.
The Katsura I potted up is fine ATM, as well as the shirasawanum in ground and potted up same time as the other Katsura.


Sorry to picture the weeds, been off work 6 months with a bad back.
This is the one I cut the leaves off of. Gets Sunlight mid day no direct Sun after 2 or 3 pm.
I sprayed at dusk so timing was spot on.




Beside the Katsura this Mikawa Yatsabusa is now showing signs. This lens cap is holding up a clump of foliage
(as Yatsabusa does) exposing the shaded area. General horticultural practices of spray timing not the case here.

Same location, East side of the house 4' from a privacy fence, this palmatum Wilsons Pink looks fine.
The other 2 with the blackened leaves are just beyond this one, hard to see.


Here is a shirasawanum Autumn Moon which are the least vigorous and the other Katsura.
This does bring one of your points up, the Autumn Moon was not leafed out, where the Katsura is the 1st to break bud
but the Wilsons Pink even earlier, making it quite susceptible to frost damage. Maybe 11 or 12 days ago we had our last frost
so far, and the maples in pots came into our unheated sunroom. It was a hard freeze actually now that I remember with outdoor
temps in the low to mid 20's F. The one that got this black leaf whatever, in ground, was covered with a sheet along with the other two
on that side of the house. The japonicum Otaki was in bud break and was not covered with a cotton sheet.3 dissectums
in the front of the house more exposed, Viridis was covered, the other 2 were not, all ok. Really makes me think it is a disease
particularly when you factor in the yatsabusas protected foliage underneath that's turning black. Pretty sure it was not leafed out when sprayed
not sure, but everything was waking up.

 

[ChristianDGreat]

I have this issue as well, any solution for this?