British Columbia: Pieris taiwanensis disease?

I've got a Pieris in a container that seems to be diseased - see attached images. It's lost a lot of leaves, but some of the new growth is not looking infected. I'm located in Vancouver where we're just coming out of a hot spell.

I've attached an image of the topside and one of the underside of a leaf. Can someone advise me what I need to do for this poor plant?

 

Lace bugs, there's even one present in your photo on the left.

 

Yikes! What do I do? I don't want to use pesticides.