On roses I use tetrasan which does not kill them but sterilizes them so the population does not increase. To be successful, it needs to be applied on roses at the first sign of damage.

On fruit trees, miticides are nasty and not really good for the average person to spray. Respirator and full spray suit needed.

Dormant oil application in spring when buds are swelling will suffocate any overwintering egg masses. Spray when
above 50 degrees but before leaf out or it can burn the young foliage.

Stacy

I mentioned mites because your photo shows damage that looks just like mite issues. I have gotten mites on apples in the past and some of my other fruits. So far, my Stanley plum has never had it.

You will not be able to see the mites well with the naked eye. Often commercial fruit growers will use a 2x hand lens to examine the underside of the leaf to check for mites.

If the damage is not mites but some other sucking insect
then an insecticide should work for control. Mites are tough to kill with most insecticides. If you rub the backside
of the damaged leaves with your finger and you get brown
streaks on your finger it most likely is mites.

I have never lost a tree to mite damage, but it sure will
reduce the growth rate of your tree this year.