Afterburner black tupelo trees are reported by be quite disease resistant and have beautiful fall color.   Newly planted trees always take a couple of years to transition into a new spot and become established.  The roots have to grow into the new area.  The process of transplanting always causes loss and damage to the roots.   It's called transplant shock.  With good care your tree should recover with these steps:  1.  water thoroughly the area under the canopy 1-2 times per week, allowing the soil to dry out between times.  2.  Do not fertilize for the first year.  3.  Stake the tree if necessary.

Plants require air as well as water.  Any plant, but especially a tree requires good, fluffy, well-drained soil.  Soil is made up of water, organic material, dirt and air.  Mixed together these materials form pores - empty areas- that water and air can move through.  This is why it's so important to have good drainage.  Water slowly and deeply with lots of water, then give the water time to soak through to the roots.  Air will follow.  The key lesson is to water deeply but less often.   Friends of Trees suggests watering 1-2 times/week.  Trees in general need the equivalent of about 1inch of water per week over the surface of the ground under the canopy, more in very hot weather.  A soaker hose looped around under the tree or a sprinkler delivers the water gently and gives the ground a chance to absorb the water.  1-2 inches of mulch will help keep the soil temperature cool, hold in moisture and discourage competing weeds.  Keep the mulch from touching the trunk.   This article from the International Society of Arborists (the tree specialists),  New Tree Planting gives more information.

 If the condition affects more of the tree and/or you see evidence of insects, fungal spots or any other sign of disease, you can send close-up pictures of the top and the underside of the leaves, or take a few leaves to your Multnomah County Master Gardener phone bank (4th floor of the Montgomery Park Building 2701 NW Vaughn St. Portland OR 97210);<personal data hidden>, mcmastergarderers.org).

OK maybe I should take some leaves in to them. I don't see any insects but the leaves are turning fall colors, especially at the top of the tree.

I attached another picutre that shows more leaves

You can certainly send in leaves to Multnomah County Master Gardeners if you think there is a disease affecting the tree. They will be able to look at the leaves under magnification.  You want the leaves to arrive fresh, so put them into a sealed plastic bag with a moist paper towel, and include a note with the information about your tree.

Leaf discoloration is one sign of Transplant Shock.  The roots are damaged, so water and nutrients are not getting to the leaves as well as they should.  By sending leaves into the office you can be more confident that there isn't something else going on as well.