what ever this is ants seem to love them for some reason... Any guesses?
Soap and water, or pyrethrin will deal with the issue.
Ive tried soapy water so far, once a week or so and so far it doesnt seem to be doing too much. Maybe safers soap?
If you have only several leaves then I just squish them with a light thumb pressure smear. Or blow them off with water pressure.
Sometimes it helps to get rid of the ants with ant stakes. They are farming them and move them around and protect them from predators. You can also put tangle trap around the trunks.
When ants aren't part of the equation the lady beetles and other beneficials usually get them in balance.