Hello, all. We have four Cunningham White rhodos that are planted in a morning sun / afternoon shade spot. For their first 5 years they were beautiful. For the past 3 years, they have been defoliating from the bottom up. At this point, there is a fringe of foliage only at the top of each shrub. Many leaves are yellow, and some have black or dark brown spots. They tend to fall off, into that familiar cigar-shape we see under some rhodos. Despite that, each year they've produced lovely bloom. This year, there are very few healthy-looking buds. Espoma Holly Tone is the only fertilizer we've used. We'd be so grateful for any of your comments or suggestions.