Q: I have been losing some Mountain Fire pieris. They start off fine but then the color of the leaves change from a dark green to green with lighter “splotches”.
A: Excellent pix of lacebug damage!
Azaleas get these most often but pieris is in the same family so they can be afflicted by the insects too.
The easiest cure is to apply imidacloprid (Bayer Tree & Shrub, Bonide Systemic Granules, etc) in March. The insecticide is drawn up into the plant sap and poisons sucking insects.
Remember that pieris can die from other causes….too wet, too dry, too much sun, etc. Make sure it isn’t being weakened from those factors.