Follow the trail back and eliminate the nest. I use a light sugar syrup with Borax powder added, works every time.
Ant like sugars. Are the fruits damaged?

For my Asian pears, when I see ants on fruit, those fruit are usually open/damaged by bird pecking or squirrel biting (when they don't take the whole fruit).

After you get rid of ants on the tree, if you don't use sugar and borax, you can wrap a masking tape inside out around the trunk of the tree and smear a product called Tanglefoot of the tape (be careful not to smear the trunk). Sometimes, I use two strips of tape overlapping each other to make a wider band.

I do the same taping on my sweet cherry trunks (after killing aphids) because ants like to farm aphids that are on underside of cherry leaves.

Or, first hose off the ants,...and afterwards snuggly wrap the inside-out masking tape on a smooth area of the trunk that will keep ants from crawling there as long as you keep sticky tape in place. I am too lazy to tangle with Tanglefoot.

Thanks so much for the info! Love the tape idea! I will sure be using that! I will get after them first thing in the morning with the hose and go from there and get them under control. Thanks so much for all the help