Answer: Based on your description I am not certain what is happening to your Rhododendron daphnoides. This shrub grows best in morning sun or bright dappled light all day with soil that is evenly moist yet well drained meaning not sopping wet or saturated. Too much sun, or soil that is too dry or too wet could cause foliage symptoms. Poor rooting can also cause sypmptoms such as you described, but there are also some diseases that could cause that.
Usually the best thing one can do for a new plant to help it establish is to water it correctly. This means keeping the soil evenly damp but not sopping wet or saturated. Using an organic mulch in a flat layer over the root zone (do not allow it to touch the bark) about three inches deep also helps. Fertilizing is not usually helpful with a stressed plant as it increases the stress by pushing it to grow. Overfertilizing can actually cause damage as well.
Since this is a new plant I would suggest you work with your professionally trained nursery staff and/or county extension to try to diagnose the problem and then knowing that, work from there. If by chance there is a pest or disease problem your county extension will have the most up to date control recommendations and can tell you what to use and how/when best to use it. Good luck with your shrub!
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