I have a plum tree( not sure which plum) have only just moved into my new home, apparently it has not Bourne any fruit for a number of years but it appears to have been infected with some fungus/disease which look like cotton wool/ fluff in its branches which then kills off the branches.
I have searched the internet but have not come across any solutions, I would appreciate if anyone has any ideas
Look up Woolly Aphids. If this looks similar the best treatment I know is to encourage blue tits and other birds to the tree by hanging feeders there. They love Woollg aphids.