Those nests may be scale. Ants farm scale similar to,people farming cows.

A horticulture oil such as neem may smother the scale. A systemic insecticide may kill the scale.

I recommend using a spray certified for use in your area for scale and ant control. In addition, I would use a multipurpose food: insecticide, fungicide, fertilizer.

That IS scale - not nests at all!! And the ants are there in response to the scale. They collect the honeydew secreted by the scale (or other sucking insects).

Scale is a serious insect problem and should be treated ASAP. What is showing in the photos is an armored scale so regular insecticides will have no real impact. They cannot penetrate the hardy, bony covering. Armored scale can only be successfully treated with insecticide when in the larval or crawler stage.....too late now to have any impact.

The tree is small enough that the scale can be picked off. You do not need to treat for the ants - once the scale is gone, they will depart also and they do no harm to the plant themselves.

I would also NOT advocate using any mixed use product. A) a spray will have minimal effect on the scale; B) if there is no fungal problem, you need no fungicide. And C) there is plenty of residual fert in the container potting soil to hold the tree until fall planting time. Just keep an eye on it to make sure you have eliminated all the scale and that it receives sufficient water.