Chemical applications? Recent hot weather?

No chemical and no unusually hot weather. I'm in ny zone 7b

Still will be something to do with conditions at mulch level.

It looks fine to me. I have several conifers that are showing the browning on the new growth at the bottom. I think it happened after we hit 90 degrees for 2 days in a row. Another possibility is that the mulch is touching the new growth.

Almost all of my weeping or skirted conifers brown on the parts that hit the mulch. I've always wondered why - I suppose it is from the radiated heat from the ground. But I've never really understood why, since it obviously doesn't happen in other places. My arborists hate tree branches touching the ground, so I just delicately prune them up so that no branch actually touches the ground/mulch but I preserve the skirt and that way I have no browning.