It is hard to tell from your posting whether the trees have been in the ground for a number of years or if they are newly planted. If they have been there for a while, then watering MAY not be the problem. Check around the roots and see if it is especially dry. Mulching would help keep whatever moisture there may be at the root level, to do some good, since I am assuming that it's more likely to be dry than wet.

If it doesn't seem to be moisture that is the problem, I would take a few branches/twigs/leaves to your county extension agent - look in the phone book under state or county agencies - and see what they can tell you. You can also take them to a GOOD nursery, if there is such in your area, and try to talk to the manager/owner. If you talk to one of the employees, they MAY not know anything - I would be slightly suspicious of any response that immediately tries to sell you "this great product", although, in fairness, you may need one or the other of the products!

If the trees are newly planted (within the past year), then probably, since you say you are in drought conditions again, they need more water. You can save the water that you run in the kitchen or bath faucets, waiting for the hot water to get there, and use that for watering - I would use most of a bucket on only a few plants, rather than a bit on all of them, as that way the whole root system will get wet. If you can't do that, then I can't think of what else it might be of use - posting a photo would help.

Just to be clear, parker, are you referring to Aesculus parviflora (bottlebrush buckeye) or something else?

Could very well be damage from last year's drought. Our area is having problems with that, too, even though this spring has been wet.