white dust type infection on laurel
We have a mysterious dusting that has appeared on our laurel tree, the trunk, branches and leaves are covered in it and the leaves are turning yellow prematurely and dropping. We have had unusually persistent hot weather here in the U.K. and wonder if this is the cause? We would love to save the tree as it is over thirty years old and offers us a great source of privacy from the neighbors. Many thanks David
Outside United States
Thank you for contacting us. As a Master Gardener in North America, I am a bit hesitant to try to diagnose your problem. However, given your hot weather and symptoms, your laurel may have scale which can cause yellowing and leaf drop. The usual treatment for scale is to spray with horticultural oil, but this is tricky to use safely in persistent hot, dry weather.
It is essential to confirm the cause of the problem in order to treat effectively. I suggest you contact a professional, perhaps a local horticultural society or arborist.
Meanwhile, do not fertilize when the tree is stressed. A surface dressing of mature compost is alright. Make sure the laurel is watered deeply once a week (keeping the foliage dry), and keep a mulch of wood chips over the entire root zone to hold on the soil moisture.