Sick elm

[camikins]

My elm has brown leaves which I assume are fungal or pest related?

Have sprayed. Should I remove all effected areas which will leave my elm almost leafless.

I'm in the Pacific northwest in Canada, above Seattle.

FWIW no other bonsai have issues and are thriving. The elm is in full/near full sun.

 

[Kanorin]

Looks likely fungal to me. Several elms (especially chinese elms) are susceptible to leaf fungus when their leaves stay too damp. For example if it's been very rainy or you give them overhead watering. What did you treat with?

 

[Tieball]

I always remove dead leaves and leaves almost dead. I dispose of the in the trash. Those dead dead leaves will not magically return to health. Buds may develop when the tree decides the time is right. It sounds like you sprayed already so best is to hope the tree returns. I had some these in the ground growing. The problem I had was dampness and a lack of air movement. The air movement eventually took care of the dampness problem. There were other trees around these so most natural air movement never really made it to these trees.

 

[Deep Sea Diver]

Argh Matey!

Sure looks like a black spot fungul issue gone wild. If the elm was previously healthy, it should bounce back. The issue is keeping the fungul infection. As @Tieball mentioned remove all major affected leaves and clean the media surface of all detritus.

In addition to the above, one might spray the remaining leaves with 2 tbsp 3% H2O2 per Qt of water every 3rd day.

cheers
DSD sends