Did you know that when Ivy (Hedera helix and all its cultivar forms) grows up into a tree from the ground, it can be detrimental to the health of the tree – although it is unlikely to kill it?
In Newlands and the Southern suburbs in general, citizens have been noticing trees that have Ivy growing on their trunks. This is especially true for trees that are on the edges of properties, street trees and for trees that have not been pruned or managed well in the recent past.
The presence of Ivy on a tree can be bad for it, but not for the reasons one normally assumes.
Common misconceptions about vines on trees are that they strangle the tree or are parasitic to the tree. Neither of these is true with Ivy.
However, self-clinging climbing plants like Ivy can compete for water and nutrients in the soil around the base of the tree and hide structural defects in tree. They also shade out inner canopy growth, and weigh down limbs.
For these reasons, it is usually recommended that climbing plants and vines are prevented from growing on trees, and removed if they are already present.
English Ivy can attach itself to the trunk of a tree with a unique ferocity and even after the Ivy has been cut off or severed at the base of the plant, it can take at least six months or more for the leaves to fall off and the rootlets to release from the bark.
If one attempts to drag it down or pull it off the trunk, the tree can be damaged as the ivy is torn from the bark. Sometimes, if the Ivy has grown right up into the top of the canopy of the tree, a professional will need to climb up the tree to remove the entire vine.
Ivy can be a particular problem if trees are very old or damaged since the dense evergreen cover may hide cavities or areas of decay and it can become an additional weight in the canopy which, in time, could affect stability of the tree, particularly in windy conditions.
If a tree has been grown for its attractive stem or bark, like the Platanus x acerifolia (London Plane tree) or Acacia xanthophloea (Fever tree), it is sensible to keep the stems or trunks free from Ivy so as not to obscure this key ornamental feature.
The presence of Ivy often indicates a tree in ill health and it may be infected with a fungus for example, so Ivy in a tree has some advantages as it can be a good indicator and signal to their carers that the tree needs to be investigated.
If you see any trees like this in your neighbourhood and you are concerned about an old or diseased tree, always ask for professional advice from a tree specialist or contact City Parks.
Alternatively, if you have Ivy growing on your verge or around the base of a tree, never let it grow up the bark and make sure that those little tendrils are pulled off when they are small.
Photo by Clare Burgess, Landscape Architect, Chair TreeKeepers