Should I be concerned about my escallonia?

I planted this escallonia Apple Blossom last October. Although the photo isn’t very clear, you can see it in the centre of the picture - showing about a foot of bare stems. What has happened to the leaves? Is it some kind of insect attack? It is in a mixed border, has plenty of space and light and has been well-looked after. The leaves further up are very healthy. Ideas appreciated.
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Growing in a container, keep them on pot feet raised off the ground in the winter time, but make sure the plants are watered if it's still warm and dry.