By Marmaduke
United Kingdom 
A twelve foot 30 year old Acer Palmatum has developed die back over the last two years to the extent of about half of it's branches - the others seem fine so far. I propose to cut off the affected branches Nov - January. Is this the best that can be done?
14 Aug, 2015
Answers
If the branches are truly dead, they can be taken off at any time. I definitely agree with Bathgate about pruning live wood, though. Any other symptoms besides dead branches?
15 Aug, 2015
Oh dear.., I do hope you don't have the issue I have. (see - http://www.growsonyou.com/fractal_cat/blog/28900-acer-ailments )
Your description is an echo of my Acer...
Fingers crossed that cutting back does not reveal the dreaded signs of infection.
16 Aug, 2015
Fractal cat and Marmaduke, A fungus-eating bacterium, Streptomyces lydicus, might help, but my feedback when I sold this was mixed. I don't know if it is available in the UK.
16 Aug, 2015
You need to find out what's causing the die back. Is something attacking the roots? 50% is quite severe. These trees are bleeders so it's best done in fall.
14 Aug, 2015