How can I help my newly planted cornus?

QOur new cornus now looks terrible. It was planted in good soil with John lnnes No3 and watered well, but it never looked happy. After three weeks I carefully lifted it and found it had made some new root growth so replanted it. Any ideas what’s wrong?

David Shead, Hastings, East Sussex

AI am sorry that your Cornus capitata is looking unhappy. You have done all the right things – planted it properly and cared well for it.

There is, almost certainly, something wrong with its roots. They may have contracted honey fungus. Check by peeling a little bark from a root to see if there is white mould beneath it.

If no mould is visible, root death may be to blame. Check by exposing a root and cutting it in half. If the centre of the root is black and dead, then this fungus