I have a rhododendron which is not doing particularly well. Several branches appear dead and the leaves remaining are yellowish with brown spots. It is currently blooming a bit. A rhodie which was planted next to it died. I Googled the symptoms and received a lot of confusing information: water it more, be careful of too much water, fertilize it, be careful with fertilizer, soil is too alkaline, bacterial or fungal infections, etc. Do you test soil or have any suggestions?