Aphid damage can look like this. Aphids can usually be taken care of with some of the less toxic methods because they are soft-bodied. Often many can be removed with a firm stream of water.

Thank you! Most of those black insects were dead because I sprayed the tree with ultrafine oil last Friday. I didn't play to spray it at all, but I still had some of the mixture left after spraying other trees for powdery mildew so I used it up on the Dynamite. It was very early dawn, so I didn't notice the damage to the Dynamite. Saw it only yesterday afternoon.

I've been spraying trees and shrubs with ultrafine oil for years. Never known ultrafine oil to cause such leaf damage. There is no connection whatsoever. It's lucky I sprayed that tree because the damage to the leaves is extensive. The tree is flanked with two rose of sharons that are pest magnets, which is why I used up the remaining mixture on it just in case something's afoot. Turns out something was.

Ultra fine oil can certainly generate phytotoxic reactions with some plants, specially if applied any time midday and in sun.

I would agree with Ken that the two issues are indeed related. If it were simply aphid damage, the leaves would be contorted or curled but not spotted! The spotting is evidence of the phytotoxicity.

I spray at dawn so as not to get lynched by neighbours. We're having an exceptionally cool spring, and two other Dynamites - they're all young and small - that I sprayed as well on the same occasion weren"t damaged. The crapes I sprayed for powdery mildew weren't damaged either.