Ii has been a VERY DRY summer and fall so they are probably suffering from drought.  Leave a hose trickling at the base of each one for a couple of hors a couple of time a week or winter will finish them off.  Also make sure that mulch hasn’t been piled up against the bark.  Brush any soil mulch back from the trunk until you find the original soil level and keep it that way.  Mulch or dirt piled against the bark of the plant slowly strangles it.