Our Nyssa sylvatica is four years old, and until today, very healthy. Today, we discovered a brown discoloration on many leaves (see photo), and on one leaf, apparent residue of a pest of some sort. It has dried brown residue with a bit of puffy white material, all attached to a slender brown stem.

We are at a loss, and very worried. It was 100 degrees today, after a fairly cool spring, and recent cool weather. We didn't see these discolored leaves a few days ago, the last time we looked.

Any ideas or suggestions? Thanks!