I'm maintaining a 30 year old, Japanese (cloud) pruned ilex crenata. it was brought from a local nursery in France, after arriving from japan 1.5 years ago. i planted it in the ground April last year.

it seemed to be accustoming well the first year.
the following April one branch started to dry out from the area closest to the main bark. first the leaves turned yellow and later fallen off leaving dead mini-branches.

i removed the branches and used pest control recommended by the local nursery. the leaves all had white lines on them.

2 months later all the branches showed the same symptoms, and large amounts of areas dried out creating big holes in the "clouds"
meanwhile all the outer regions of the clouds grow very good and fast.

i cleaned away all the dead branches and noticed 2 or 3 places where sprouts are coming out again, however leaves are still drying out inside, while growing nicely outside.

please any advise will help.
thank you very much