I have a plum tree, approximately 8 years old. During initial two years, it has provided nice crop of fruits, around 100 plums but after that it's almost a period of four years it doesn't blossom/carry flowers. During its fourth year, it got many black flies sitting on its branches in groups extracting oil from its main stem and main branches. I used an insecticide to wipe out. During next year, the plant started giving out gum from its stem and thereafter no flowers are growing on its branches, rather the plant is carrying lots of leaves. Please help me to come out of the problem.
No Flowers on Plum Tree
Certified GKH Gardening Expert
The oozing sap you refer too is a common issue with Plum Trees, your tree may be infected with a fugal or bacterial disease.
Here are some links to help you.