Helen Yemm: plum problems, wilting Judas, support for trees – Telegraph.co.uk

Cercis uncertainty

In the last four to five days my Judas tree has developed a patch of browning, dying leaves, mysteriously on one side only, with no sign of an obvious cause. Rosemary Whitt, via email

The picture you sent showed amature Judas tree (Cercis siliquastrum), one of whose two stems seems, as you fear, to be dying. This sudden collapse is possibly due to verticillium wilt to which this cercis is susceptible. Various wilts are responsible for all sorts of tree and shrub deaths: cotinus is notoriously prone and I have a friend whose mighty Eleagnus Quicksilver went this way, a branch at a time.

It is hard to be sure about wilts. If you chop off an affected branch, there may be a telltale brown/black stain running trough the wood which would indeed indicate that it is the cause of the problem, but if this is not obvious it is tempting to think that there may be something else wrong that will miraculously right itself. You could try to stay ahead of the game by removing the dying half of the tree. You might just save it, while leaving it a rather strange shape from which it might recover in time. I presume you have already taken a good look at the tree at ground level, to see if it one of its trunks has somehow been injured realistically, the only other cause of the problem.

I am planning to plant an ornamental birch in my garden in the autumn and have been looking around at the many different ways other people support their trees. What do you recommend? Anita Oliver, via email

Researchers have found that young tree trunks will thicken up more quickly where they are allowed to bend slightly in the wind, so depending on the size of your tree and on how sheltered your garden is, it may not need staking at all. However, if necessary, a short, slanting stake is recommended for container-grown trees, while a short straight one is suitable for those that are planted bare-rooted. The reason is logical: it would be easy to damage the roots of a container-grown tree by banging a stake right through the middle of the root ball. However, a stake driven in at an angle after the tree is planted avoids this risk. The top of a slanting stake should face into the wind, and a straight stake should be on the windward side, too, with 2ft (60cm) of the stake below ground and about the same above.

Tree ties are often wrongly fitted. You can see exactly how this bit of kit is used on YouTube look at Sue Beesleys demonstration How to fit a tree tie. Ties should be checked and adjusted annually. After three years the tree should have made enough new roots to become stable, and stakes can then be removed.

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Helen Yemm: plum problems, wilting Judas, support for trees - Telegraph.co.uk