@stu_crawford i thought Exobasidium parvifolii in the field but changing my mind now for sure.
Seems like a virus or fungus is causing intensive growth and death of additional sprouts.
Spotted on my journey as a National Geographic Grosvenor Teacher Fellow 2018. British Columbia
These large black slugs were everywhere in this field, every 2-3 footsteps I had to sidestep to not step on them.
Good day to cross the road.
I believe this is part of the mating process