at that height.. i think dog.. it would probably have a smell ... which i should not have to further explain ... lol...

just track it back into the plant .. and remove that branch ... back to a green shoot ...

could also simply be shipping damage.. just now showing ...

ken

in hindsight.. i dont understand the pic ....

there is the obviously brown part i was speaking of ...

but i cant tell if the rest of the pic has lesser browning.... or its a poor camera shot ...

if the rest is also browning... you have some serious water issues ... either too much [your root rot theory] .. too little.. or improper planting .. or finally.. poor stock to begin with [like severely potbound] ....

but.. having no history in regard to any of that.. i cant go further ...

no one ever said two plants will react to transplanting the same way .... one would think so.. but one can not assume such .... [it kinda leads into the fact that one may have been poorer stock than the other at purchase????]

ken