If these are sweet loving ants then feeding them "Terro" may solve your problem. Just fill up a bottle cap or 2 with Terro and the ants will drink it up and feed the queen. All ants should be dead in a week or so. Terro is a liquid which is basically sugar syrup and boric acid mixture and can be found at most hardware stores.

That isn't ant damage. I would research more deeply to figure out the problem. Doesn't look like fertilizer burn. Maybe water damage, but it only took one branch and the rest looks fine, so...Hmm.