Ivy on Trees - Good, Bad or Indifferent?
Common Name: Common ivy
Botanical Name: Hedera helix (helix is ancient Greek meaning 'twist' or 'turn')
Habit: Ivy is the only native British evergreen climbing shrub.
Ivy is dimorphic, meaning it has two forms. When the ivy is juvenile (figure 1) it has the characteristic lobed 'ivy shaped' leaves that are particularly well adapted to living in low light conditions. When it is mature (figure 2) it produces side branches with elliptical leaves and flowering shoots. This mature form will usually only develop where there are good light conditions.
The mature growth bears yellow-green flowers in autumn and black-coloured berries the following spring.
The most effective way of controlling ivy is to cut the individual stems near to the base of the tree. It is advisable to remove a section of each of the stems, to reveal the tree trunk below, in order to be certain that each stem has been cut.
The severed stems can be chemically treated with ammonium sulphamate, glyphosate or triclopyr to prevent any re-growth if necessary.
Ivy is an essential part of the wildlife habitat, providing food and shelter for a wide range of birds, insects and mammals
- The flowers provide a source of pollen for bees and butterflies into the autumn.
- The berries, which ripen in March/April, have a high-fat content and provide both native and migrant birds with an early source of food.
- The stems provide a safe haven, nesting and roosting place, particularly during the winter months.
Ivy is not parasitic and does not directly affect the health of the trees. Its supplies itself with water and nutrients and only uses the tree as a means of support to reach the light.
A heavy infestation of ivy throughout the crown of a tree is, usually, but not always an indication that the tree is in a state of natural decline. In these circumstances ivy can smother a tree and hasten its decline.
The dense adult growth, throughout the crown, will then have a tendency to make the tree top heavy and therefore more likely to fail during adverse weather conditions.
A dense covering of ivy on the trunk and throughout the crown of a mature tree can prevent tree inspections by obscuring cavities, the presence of decay fungi and the structure of the tree.
Ivy is an essential part of the wildlife habitat, however there are times when it is advisable to control its growth and development. It will rarely, if ever, be necessary to control ivy in a woodland situation, however it may be desirable to control it in parks and gardens and where it prevents tree inspections.