Failed airlayer on Shishigashira

[Steven1969s]

Hello everyone.

Can anyone here tell me a possible reason why an airlayer can fail and also, what would cause the airlayer part to turn brown?
I also included pictures of another airlayer on same tree that remains green.
Both airlayers were started in the middle of May of this year.

Thanks for your help.

 

[BrianBay9]

The most obvious way to fail with brown foliage above is to cut too deep, cutting off the flow of water from the roots.





You want to remove the section of vascular cambium, but keep the "sapwood".