Thank you for your question, as well as the excellent pictures.  I agree that your tree appears to have a blight, caused by a fungus that probably overwintered in leaves and other debris in the area, and then splashed up to the emerging foliage.  Did you apply any type of dormant sprays to treat this during the winter, as suggested in this Extension publication?  There a number of pathogens that cause black spots, yellowing and curling of the blooms, only a few of which can now be treated.

I suggest you cut some samples off, and take them to the Washington County Extension office, whose contact information you can find here.  They can examine the plant tissue under a microscope to confirm a diagnosis, and offer help to solve/prevent it.  Hope this is helpful.  Good luck!

I didn't treat in any way  but put down hemlock mulch. 

If you look at the article I referred you to, you can see there are several preventative measures. If you didn’t use them, an even better reason to visit the Extension office!