Lilac tree in trouble

Asked July 20, 2017, 10:02 PM EDT

I have a young lilac tree I planted last fall. It has done well until very recently: It's leaves are curling. They have black spots developing and look like something might be nibbling them, except that I can't find any insects. I tried a home brew of water with oil, dish soap and a touch of vinegar. As I rubbed some on the trunk and branches, I found grainy stuff, especially in the places where branches leave the trunk. What might this be? Also, would rose food be good for my tree?

Union County Oregon lilac horticulture

2 Responses

Thank you for your question. It would be helpful if you could take some photos of the problem areas, as well as one of the entire tree, and attach it to a response. I think the issue is not one of food/nutrition, but of a fungal or bacterial issue. How long ago did you first recognize the problem? Thanks for more information.

Just following up on the previous response. Yes, pictures would definitely be helpful to make a better diagnosis. There are several possibilities if your problem is a fungus or bacteria. Key things that you can do to start with are pruning branches for good circulation in the plant and watering at the base of the plant, rather than through overhead irrigation. Below are several links that you might find interesting that would help in making a diagnosis and treatment plan.

Leaf spot: https://pnwhandbooks.org/node/3028/print

bacterial blight: https://pnwhandbooks.org/node/3025/print

pruning lilacs: http://extension.oregonstate.edu/gardening/prune-lilacs-soon-after-bloom