Asimina triloba 'Potomac' has a problem
In April of 2015, I planted 2 pawpaw trees: Potomac and Susquehanna. Both have flourished---until this year. During the rainy spell of May and June, I noticed that Potomac had one branch on which the leaves seemed to be droopier than usual. After a period of time, the leaves wilted and died. Yet, at the same time, it was putting out new branches and leaves fairly vigorously. It continues to do this. I have attached photos which were taken on 4 July 2018. Can you tell me what is wrong with the pawpaw and what to do about it?
Based on the photos the tree may have a trunk or root issue. You will have to look for this. We had a drought and excessive rains and this can stress the tree.
Make sure they are not planted too deeply, you should be able to see the flare of the trunk where it joins the root system.
Also, make sure mulch is no thicker than several inches and keep away from the base of the trunk. Check the soil drainage and make sure the soil drains well.
Check the trunk and make sure there is no damage to the trunk. Bark can be damaged by frost cracking, excessive mulch, feeding by voles, rabbits, etc. All you can do is prune out dead plant material and monitor the growth of the trees.
See our publication on these types of problems http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...
Also, here is a publication from Purdue on paw paws https://ag.purdue.edu/hla/pubs/HO/HO-220.pdf