Just spray with a strong stream of water first. That is typically the easiest and most efficient way of dealing with aphids on trees and one that does not threaten any beneficials as well.

It may not remove the entire population at once so do again in a day or two. Aphids really do nothing more than cosmetic damage to an established tree so I would hesitate to use any sort of pesticide......just not that necessary.

Ok. Thank you. Then I have something else infecting my tree? Because it's shrivllin up an do

Aphids focus primarily on very succulent new growth. And their feeding habits (they suck out plant juices) will often result in leaf distortion. But that only affects appearance, not the health of the tree.

btw, older foliage looks fine :-)

OMG. That is awesome to here! Thanks a bunch. A bunch of plum!! Lol

While your helping...do I prune this tree?

What sort of plum is this? It has the appearance of an ornamental purple leaved plum, rather than a fruiting plum. Did it have pink flowers? How large do the fruit get?

I wouldn't worry too much about pruning. Plums require very little compared with apples or pears and can crop well with little to no intervention. If it is an ornamental it needs none, other than removing dead , damaged or ill placed growth.

Curiously, stone fruits are pruned in summer where I live, to avoid silver leaf disease.