Can anyone tell me what fungus this is and what product I need to cure it? Thanks so much.
If I were you, I wouldn't worry about the leaf spot now. Your rhododendrons (other post) desperately need to be lifted, root balls opened up, replanted in a looser environment. If not, those roots will continue to grow in a circle pattern as formed by the pots and they will die. Right now, they look quite dry, you may even want to plunge them into a bucket for several minutes before you put them back into the ground, it appears that tight rootball has been repelling rather than absorbing any water. Don't leave them soaking overnight or longer, rhododendrons can drown, but try to completely moisten that rootball.
Then mulch with something organic when replanted to cool the roots and conserve moisture.
The fungal spots aren't your biggest issue. Few fungicides are curative, better as preventatives. You may want to spray with a fungicide as the new foliage buds are expanding and opening later, or with a corrected planting, less stress, they may resolve it themselves. Get them planted correctly, worry about the leaf spot later.
I concur with Morz8 completely. Plants that are weakened by improper culture are more vulnerable to all problems.
Just saw these pics and I'll third that. When you have pronopunced severly compacted soil, it's not going to promote healthy growth for rhodies. I can literally pull dandelions (with an 8" tap root) by hand out of my beds - your soil should be loose, loam and when planting, you should almost tear up the ball as it's developed in the growing container. I'm sure if you dig that Cunnigham White up, it will probably have just about the same root mass (from the container) still in place.
'black earth live again'