What can I do to save my fruitless plum from an unseen insect that is eating the leaves and killing the tree?

Question

The tree is   5 years old

Answer 1

for this now. wait until the sun goes down and the tree cools off and mix up 2 tablespoons dawn & 1qt of water and spray, get under & on the leaves, if it rains do it again.  in The fall do dormant oil for fall, in early spring do dormant oil for spring application...............it it gets buds spray up to bud stage, if & when buds open stop spraying then spray the trunk.  I stop because of the bees.  We plant flowers to draw the bees for polunation.