Summer Branch Drop and “Leaf Spot” on Cherry Trees

After all the heavy rainfall recently, we have had some reoccurring tree problems which may not seem related to the weather.

I’ve experienced two incidences of cracking and splitting stems in the last two days due to the sudden, heavy downpour being transpirated by mature trees. One in Linlithgow on a Beech tree that nearly prevented a Forestry First Aid course from going ahead and another on a mature Oak overhanging a road in Mount Vernon, Glasgow.

Water is taken up by the roots and carried up through the Xylem as normal but due to the excessive rainfall trees are affected when the amount of water they take on board becomes too much and the additional weight sees vulnerable weak parts of the tree’s structure breaking under the strain.

This is known as “Summer Branch Drop” and usually occurs during dry weather when there is a sudden heavy downpour.

The other problem I’ve observed is black spots on Cherry leaves which is simply referred to as “Leaf Spot”.

I was called by a client in Livingston yesterday who was concerned about his row of Cherry trees that he planted outside his home. He values them greatly and wishes to see them grow and thrive as his family grows.

He had noticed some unusual symptoms that gave him cause for concern and he contact me to arrange a visit.

Although he is not growing the trees to produce the type of fruit associated with warmer climates in Italy or Turkey they are valuable to him and he enjoys the light dissipation, privacy, shade, separate zones in the garden and of course the beautiful flowers in Spring time.

The spots are caused by the fungus Blumeriella jaapii when the spores are released during rainy periods. The first sign of which is yellowing leaves, followed by the black spots and then early leaf fall.

Whilst the site is well drained and reasonably well aerated we have had sudden extreme wet weather combined with a relatively cool summer; just the conditions favoured by the Fungi.

One of the solutions is to ensure that the Fungi is not allowed to overwinter in leaf litter so all infected leaves should be destroyed upon falling. This is crucial to controlling the effects.

There may also be some efficacy is applying straw mulch bedding to the immediate rooting zone after all leaves have fallen and been picked up.

As a side issue, it was obvious that the characteristically close to the surface roots were being damaged by mowers and strimmers so we discussed how to avoid this and if possible ameliorate the current condition of the roots.

Top dressing with soil up to a couple of inches may hide the roots but in order to halt the behaviour that is causing the damage I recommended not cutting the grass with machines around the area where the roots are most prominent but instead hand cutting the grass or allowing it to grow slightly longer. I had considered mulching the base but I thought this may look unsightly when the grass started to grow through and it would be easy to use too much material and suffocate the roots.

It will be interesting to see the effects of this advice and I hope the client can implement this plan to ensure the disease symptoms are brought to a halt.

I enjoy being challenged and having to learn new solutions that might not necessarily involve Tree Surgery but that are more aligned with the principles of Arboriculture.

Do you have any tips or insights to add that you have known to be effective?

If so, please share them with me: This email address is being protected from spambots. You need JavaScript enabled to view it.

Thanks
David