Answer: Salix integra 'Hakura Nishiki'is a willow and like all willows is very happy in moist to even wet soil, so I do not think excess rain would have had an adverse effect in that sense. This group of plants however is subject to numerous foliage problems including fungal infections, and the damp weather could encourage these to develop. In my experience, too, stressed plants (transplanting then frost) can be more likely to be attacked than more established vigorously growing plants. I would suggest you take a sample affected interior branch and possibly a few photos to your county extension or to the nursery where you purchased the plant and see if they can identify the problem for certain and suggest steps to take next. I'm sorry I can't be more specific with a diagnosis long distance. Good luck with your shrub!
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