I have five large trees in the back garden. Recently, I can see that most of them are getting yellow leaves and I don't know what to do. Can you advise, please?
Yellow Leaves on Tree
Certified GKH Gardening Expert
The yellowing of leaves can indicate watering issues; either too much or too little.
How has your weather been? Rainfall heavy or drought conditions?
Also you will need to examine the tree more closely. Yellowing of plant material can be signs of pests or disease. Examine the trunks, branches and leaves.
I can't make any determination from just this image.
You can take a leaf sample to your local County Extension Office for examination.
They also will have information on the weather effects on trees in your area.
Here is a link to help you locate your nearest office.