Julie is there any chance that it is due to wind? I have had trouble from time to time with all of my maples (both the palmatums and the shirasawanums) if it is super windy when the leaves are very young. They crisp around the edges. My A. shirasawanum 'Jordan' looks a lot like your 'Autumn Moon' and in my case it is due to wind. May is our windiest month so the wind often comes at a time that the leaves are tender.

Re: the pot - I have 'Autumn Moon' in a pot (bigger pot than yours, but my plant is also bigger). If you make sure to move up and/or root prune periodically you should be ok (and make sure it gets enough water).

thanks for the reply! and I'm glad to hear that you have had success with yours in a pot :) We haven't had wind here but it can be very easy to not water enough when it's grey and chilly...it just doesn't feel like things need much water. I will give her even more and roll her out of the sun...when we get some...for at least part of the day. Do you have yours in mostly shade in your zone?
Julie

My 'Autumn Moon' gets shaded from the last few hours of sun;'Jordan', which is much paler-leaved, gets shaded for about 1/2 a day.

One of the things that I find tricky is that problems can occur when the leaf is unfurling and I don't happen to notice what is going on that day(s). Then when I notice the leaf, it has damage that is likely abiotic (wind, sun, humidity issues, etc) but I can't remember what the conditions were. Generally speaking, it is a lot easier to kill a plant in a container by underwatering it than overwatering it, but it has to drain well.

Keep us posted!

Sara

To me, those photos look most symptomatic of what happens if we get a good frost right when the leaves are unfurling. JM's and other Asian maples with somewhat pale, delicate foliage - like Autumn Moon or Golden Moon - are rather vulnerable to cold damage at that stage. Late spring frosts are pretty common in the PNW :-)

I wouldn't worry about it - nothing systemic to the tree itself and the heavily damaged foliage will be replaced. I agree with Sara that Autumn Moon is not as sun sensitive as some choices. Mine in a container is in pretty heavy afternoon sun but I've yet to notice any scorch or leaf damage from that setting. And it does get exposed to a fair amount of wind as well in my beachfront location.

Thx gardengal, once again proving that local expertise is the best! It looked abiotic, but down here I did not think of late spring frost (although we once had one on April 23) - wind in my part of the world is the late spring issue.

My A. palmatum 'Baby Ghost' was really ripped apart by wind one year and I took off all of the damaged leaves - they were absolutely shredded - and it leafed out again within a month.

thanks to all for your input! I am happy to hear that she isn't diseased and my choice of Autumn Moon for a container isn't totally wacky :)I will make sure to give her more water since she has very nicely draining soil and will pull her under the awning during our hot times as she is in the sun all day and has heat radiate off the deck. No one mentioned thinking that the sedum in the pot was a problem so I will stick with that too. I can't wait for it to spill over and be against the old copper of the container.

OK, now you've piqued my interest! You are growing this tree in a copper container? Is it solid copper? Lined at all?

Excessive copper - and copper materials do oxidize and leach - can create toxic soil conditions. Plants have different tolerances for such things but JM's tend have pretty low tolerance for anything out of the ordinary :-) Not saying that is what is happening with your tree but it is most definitely worth monitoring. If the problem continues throughout the season despite attention to watering and/or sun protection, I'd seriously consider a new container.

gardengal see photo on original post - the maple is in a plastic pot which is set inside the copper cachepot.

Excellent!! Just ignore everything I said in that last post, then :-)