I have 3 plum trees, 2 oulins and 1 opal. All were laden with fruit til 3 years ago when the Opal stopped. Then the gages stopped the following year. All are completely healthy with no disease. To my horror I read the fruiting life span is 20 to 25 years which is roughly how old they are. They are medium size in height grown on St Julien rootstock. I decided to take drastic action and hard prune them last summer and now young shoots are appearing on the pruned large branches. Will these trees ever fruit again, say next year or am I wasting my time and have them removed?