Please post pictures.

As I said, "Sorry I have no picture but will get that next week [when I'm at the garden again] if no one here has an answer before then." Didn't have my camera last week, won't be back 'til the week-end. The plant has kind of a distinct pattern, which I described, not spotted like many problems, not affecting the leaf edges, but coloring either side of the main vein and, I might add, deforming the new growth somewhat -- wrinkling, twisting end a bit.

You have deciduous azaleas that bloom in August?????? What are they????? I know prunifolium blooms late in the season, but that is very late.

I haven't seen the problem you describe.

Some leaf spots are caused by a virus thought to be a potexvirus, the most common ailment being called Necrotic Ring Spot. The symptoms are reddish-brown rings or spots on the leaves. It generally occurs only on the two year leaves of a few rhododendron cultivars such as R. 'Unique', or on Kalmia latifolia. It also appears on the first year foliage of some R. 'Loderi' clones. Little is known about the disease and a does not seem to spread from one cultivar to another. No control is known or generally necessary.

Small bright yellow spots is a symptom of Azalea Rust, Puccininastrum vaccinii, a fungal disease. Orange-red pustules containing spores form on the lower surface of the leaf. This rust is only sporadically severe and typically infects deciduous azaleas. Control by avoiding those hybrids and species which are very susceptible to rust. Good air circulation is helpful. Triadimefon seems to help, but may not be registered for use on rhododendrons.

Thanks rhodyman. Mine have not yet bloomed, but I see the species R. prunifolium described as blooming anywhere from July through early September. I grew mine from seed provided by the New England Wild Flower Society, which, as I recall, said they bloomed in August in our region. The one, now in bad shape, which had flower buds for the first time this year, was holding on to them tightly.

The leaves definitely don't have rings or spots or browing on the edges, but a pattern mirroring the internal vein or veins. I'll keep an eye on the situation and post a picture this week-end. I have nearby Kalmia and high-bush blueberry which show no symptoms.