Question:

I am writing to you in the hope you can advise me about my rowan tree. A few weeks before Christmas I realised I had a clump of mistletoe growing in it. When I looked more carefully I found there are five or six clumps in the tree. Since then I have read or seen on television that such growths can kill the tree and advised cutting the affected branches off. Do you think I should do this? (Mrs G Smith, Swardeston)

Answer:

Mistletoe (Viscum album) is an evergreen plant that is smothered in white berries from winter to spring. It grows in the branches of trees, such as hawthorn, apple, poplar, lime and conifers. Mistletoe is a parasitic plant that lives off the nutrients and water from a host tree. Although it is parasitic, it will not kill the host tree. Rowan can be slow growing but as long as your tree is of a reasonable size the addition of the mistletoe is a bonus – especially at Christmas! The berries are often spread by birds from one tree to another, and this is how the large rounded clumps of mistletoe form in tree branches. The most common host tree in the UK is apple, but poplar and lime are also frequent hosts. It is mainly found in the South and West Midlands in the UK, with particularly large populations in Herefordshire.

Most mistletoe on sale comes either from the UK or elsewhere in Europe. Look for plants that are freshly gathered (if necessary, ask when it was harvested), with fresh green foliage and ripe white berries that are plump and not withered. Mistletoe will keep for two to three weeks after gathering if it is kept in a cool place such as a shed or garage. Do not attempt to gather mistletoe without permission from the landowner.

Although mistletoe is spread naturally by birds, it is possible to grow it yourself.

Here's how: Harvest berries from a tree in March or April. Make sure you choose a tree that is similar to the type of tree in your own garden that you wish to establish the mistletoe on. Discard any crushed berries and do not use berries from sprigs used as Christmas decorations. These will not germinate as they are harvested when immature. Choose a branch 10cm (4in) or more in girth on a tree that is 15-years-old or more. Ideally this should be fairly high up, so the plant receives lots of light. Make a shallow cut to create a flap in the bark. Remove the seeds from the fleshy berries and insert them under the bark flap. Finish by covering the flap with hessian to protect the seeds from birds. Sow quite a few seeds under each flap of bark as only one in ten seeds germinate, and both male and female plants are needed for berries to form. Don't expect quick results; plants can take five years or more to reach berrying size.