British Columbia: Corylus cornuta var. californica = leaves dying

2 Years ago I bought a small one gallon Corylus cornuta var. californica from the Swan Lake Native Plant Sale in Victoria, BC. The plant was small so I kept it on the NE side of my house in semi-shade and potted it up until it was 4' high and in a 4 gallon pot.

In mid-March I planted it out on the NW side of my house in a semi-shade that gets a few more hours of direct sun. Yesterday I noticed some sever damage to the newest leaves at the top of the shrub. See the photos below.

Can anyone suggest what this problem might be?

I feel it's powdery mildew or a combination of inconsistent watering which has led to a secondary problem of a pest making holes in the leaves leading to their death. But, I wonder - could this be a blight?