I bought 2 chinese elms from a reputable bonsai merchant. The one i have is
absolutly fine, it will need repotting this year but otherwise it is in fine
health. The other one has a problem. Again it needs repotting but the leaves
have started to go yellow and i can't understand why. I have treated both
trees exactly the same in regards to position, temperature, water and
fertilizer (the last 2 when needed) and like i say the one is fine yet the
other is clearly in trouble. The exact symptoms are that the leaves are
going yellow with green spots. It was sold to me as a sub-tropical tree and
i have kept it as warm as is needed. Thanks in advance for any help offered.

Oh and i have checked for all the possible pests like aphids, spider mites,
ants, scale insects, weevils and all other manner of things so i do not
think it is anything like that. I know i have not overwatered and like i say
the other tree is fine so i have treated it right. Thanks again.