Normally you prune out the blighted branches immediately to stop infection. Next Feb/Mar open the Blueberry plant up by pruning out branches around the middle of the plant - this allows air to circulate around.

Many thanks for your help, I will prune the blighted branches immediately and then leave until next Feb/March. Hope blueberries will be o.k. Many thanks.

Is the Blueberry doing OK? My ones are not exactly excelling themselves this year.