Question

  QUESTION: This past winter I noticed these white spots on the bark of my lilac. This spring, the leaves came out very late and were curled up at the stem of the leaf. Some of the blooms are affected also, what ever it is, it has spread to my other lilacs, even a common lilac. Is there something I can do to treat the problem?

ANSWER: Hi Jackie:
Sounds like you may have two separate issues. White spots on bark and twisted leaves/blooms.  I do not see anything on the leaves in your photo, but look closely on the undersides for anything like insects etc.  The twisting looks somewhat strange, like a growth abnormality.  Have there been any herbicides (weed killers) used in the vicinity over the past 1-3 weeks? Sometimes some of these materials can cause these effects.  Spraying these products on a windy day can cause contact with sensitive plants.  I do not see any evidence of disease on the leaves/blooms. I'd would look into the herbicide possibility.

Not sure about the white spots. Send a closeup photo and I'll have a look at that as well.

Steve

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  QUESTION: Dr. Vann

Thank you so much for your quick response. There was weed killer used in the vicinity, although if I remember right, the plant had not leafed out yet. Would that make a difference? Attached is another photo of the trunk of the plant.

Answer
Jackie:
I suspect that these white spots may be a superficial fungus/algae like a lichen. These are not disease organisms. On the herbicide issue, there is a group of weed killers that are called growth regulators.  These materials like for example those that contain 2,4,D cause weeds to twist and grow themselves out of control and die.  Tomatoes are very very sensitive to this group. Leaves become unrecognizable!! Herbicides like "Roundup" brand are not of this type.  If there were buds present on the lilac, injury could occur.  If the dose wasn't too high, the lilac should grow out of the problem over time.

Steve