(Ken, before you say it, I know: you can't kill willows and if it's alive you're doing fine, lol. ;-) ===>>>> lol .... light frost .. can cause minor damage.. that doesnt appear for days .. especially if nights are very cool .. or until a heat wave .. hence the term light.. and minor ... so a little leaf browning is NBD .... transplant shock. or stress is MINOR ... if it doesnt show up for days or weeks .. or until heat wave ... so which is the cause.. how the heck do i know ... one is leaf damage from lack of water due to interfering with the roots at planting .. and the other is leaf damage from cold ... one ting for sure.. white tissue is the easiest to harm ... all that said .. based on new growth.. the only thing that seems currently stressed is you .. take a chill pill ... as you note.. its a darn willow .. lol ... btw: i always wanted to see if i could root cuttings off one of these ... since willow generally roots easily and fast ... and since soon enough.. you will probably be beating it back with a truck ... maybe you can try to do it with some of your prunings.. just to find out ... and i doubt you can over water a willow .... other than proper watering .. and i doubt you can over water a willow .... i dont see what if anything you need to be doing.. beside the noted self medicating.. lol ... ken

duplicate post.. answers started here: https://www.houzz.com/discussions/5990676/dappled-nishki-willow-tell-me-it-s-not-a-goner-z6a-ne-oh#n=3

from a distance.. the soil looks bone dry ... put a hose on a trickle.. and water it for a few hours.. moving the hose every half hour or so .. we want water 2 to 3 feet out.. from the hole you dug.. and the hole you planted it in .... the lawn does not look in drought.. but you cant water a new transplant with lawn irrigation.. if any .... see link below on watering ... do you have that horrible OH clay.. or will the hole you dug drain properly???? it incredibly stressed ... due to transport.. planting.. and lack of water.. its not hungry.. no fert until spring.. if ever .. its a deciduous tree .. within a month.. all the leaves will fall off.. the stress is making that happen a bit early ... look to the growth ends.. rather than the interior ... its sacrificing so of those leaves to maintain the outer younger leaves ... look close.. and see if you can see next years buds.. as long as those stay green and hard.. you should be all set for next spring ... in the midwest.. you should never plant anything in august .. hopefully the cool wave will hold .. the key is cool/cold nights ... for a recovery period after a hot day .;.... see link for a good primer .. you should get some good clues to watering.. etc ... and in case you plant a tree again ... other things you might do differently .... ken that stalker in the second pic look stunned by the tree ... lol ... https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

Despite the fact that it looks like a tree, it is really just a shrub grafted to a straight willow trunk. It will never get too much larger than it is now and does not present an aggressive root system. Your spacing should be OK. In its regular shrubby form, the dappled willow could get as much as 6' tall and 4-5' wide so you can expect the top grafted portion to attain a similar size without pruning. Will definitely require consistent pruning to keep the top in scale with the trunk.