Today’s article is about Silver leaf, a fungal disease which affects both the wood and the leaves of certain species of trees, specifically plum, apple, apricot and cherry trees.
The fungus enters the tree through wounds in its exterior – which is one reason why it’s so important to be careful when pruning, and to check your trees after high winds or floods as a gash in its bark can be the weak point that infections and infestations could exploit, risking the health and even the life of your tree.
Once inside Silver leaf causes a silvering of the tree’s leaves and eventually, the death of the branch. The fungus responsible is a spore known as Chondrostereum purpureum, which is most active from September to May each year.
Spotting the symptoms of silver leaf
- On leaves: If you notice a silvery sheen on the leaves of your tree, especially prominent in plum trees, watch out for the health of the branches around it. If the affected branches begin to die, you may have a problem.
- On branches: A trick that tree surgeons will use to determine the cause of a sickness in a tree is to cut across the affected branches to see what there is to see inside. If you notice an irregular dark stain in the centre you may have a problem. This is actually wood which has died as a result of the spore. On older dead branches, you may also see bracket-shaped fungi begin to appear. These are characterised by a whitish woolly upper surface and a purple-brown lower surface with fine pores.
There are a number of other causes of similar silvering symptoms, such as cold, drought and other forms of stress. The best way to distinguish between so-called ‘false silver leaf’ and the real thing is to consult an expert.
Controlling the spread without chemicals
Do your pruning in the summer months. On trees that are most susceptible to this fungus it makes sense to prune in the months when the fungus is least active, outside of the damp conditions of autumn and winter. Careful pruning with properly sharpened equipment could also minimise the potential of infection. Wounds caused to the trees during pruning in the summer months will also heal more quickly.
If you have a confirmed case of silver leaf, the affected branch needs to be removed as soon as possible, before any fruiting bodies appear, as this will only accelerate its spread. The branch should be cut off, where possible, at least 10–15cm (4–6in) past the point where you stop being able to see the staining on the tissue inside the branch.
When dealing with silver leaf, it is vital that you frequently disinfect your cutting equipment and dispose of anything pruned from the tree immediately to stop the fungal fruiting bodies from forming on the removed material which could see the cycle starting again.
There are also chemical options that can help stop the spread of silver leaf. While in many cases of infection, control chemicals should be avoided, in trees susceptible to silver leaf ‘wound-paints’ and seals can offer some degree of protection from the spore.
If you have spotted any of the symptoms of silver leaf infection on your trees, call us on 0208 292 8992 and we’ll happily pop round to give you our professional opinion for your peace of mind.