Have you tested your soil? We have several two-year-old rhodies that first exhibited leaf curl, then the leaves turned brown and the entire
plant eventually died. We were worried that it was root rot, which would have been awful since we'd read that the responsible fungus is almost impossible to eradicate from the soil and any future rhodies planted in that spot would likely contract it. We described the problem to our county extension officer who diagnosed it as a soil pH problem. Sure enough, when we tested the soil it was around pH 7. We just treated it with garden sulfur in an attempt to bring it down below pH 6 before we try replanting in the fall.
BTW, our county extension officer has helped us with with lots of issues we had with new landscape
plants. If you have such a service in Oregon, I'd recommend taking a cutting of the affected
plants to them for analysis.