Growth on dwarf lilac bushes
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Growth on dwarf lilac bushes

by Linda S.
(New Jersey)

White substance on lilacs

White substance on lilacs

There is a soft, thready, white substance that has appeared on my dwarf lilac bushes in the last week or two on the northfacing side of the bushes. The most recent rainfall was three nights ago, rainfall has been sporadic, brief thunderstorms that are normal for this time of year in NJ.

The white material rubbed off easily when I tried to remove some and the bark beneath was softened and stained my fingertips a light color. There was what appeared to be spider silk-like threads between my fingers afterwards, but no visible insects or arachnids that I could see. The photograph was taken last night which is when I originally submitted my question. Doug suggested I upload the picture here instead.

Any ideas what is infesting my lilacs? How do I remedy this and save the bushes. The lilacs were just gorgeous this spring.

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Growth on dwarf lilac bushes

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Success!!!!
by: Linda S.

Thank you to all who left comments to help me get my lilac bushes healthy again.

I took your advice and used an oil I picked up from the garden center, that application was about two weeks ago. There hasn't been any build up of the white fluffy material on the lilac's bark since and I'm also noticing that some of the curled leaves are beginning to uncurl and regain some darker green color.

Again, thank you so much!!!
White scale
by: Moni

Wow, after identifying your scale problem, I have found some on some of my shrubs while out pruning. Not a big problem, but interesting to see!
Tiny black bug
by: Moni

If you only found one little black bug then it is not it...there should be many. It would be good to have a photo of the leaf curling...is there white stuff on the leaves??
How much of the plants have white stuff on them?
Thanks.
Yes on the curling leaves
by: Linda S.

Leaves at the tops of both lilacs are beginning to curl along their long axis, around the midrib. The affected leaves are lighter green in color and the curling is toward the underside of the leaf. I can upload another picture if my description isn't good enough.

I removed some of the white material looking for obvious insect activity and found a very tiny black insect. Much less than a mm in length. No idea if that wee guy is in the "wrong place at the wrong time" or the actual culprit.

Have not yet had the chance to try the oils as described.
White stuff
by: Moni

Well, it is possible that it could be woolly aphid. They feed on leaves, buds, twigs, and bark. Aphids leave a waste product that is sticky, called 'honeydew'. This can then develop a fungus that is black called sooty mold. Fortunately, heavy woolly aphid infestations only occur periodically and are usually controlled by natural enemies.

The photo does not show the white stuff to be as puffy or insect parts/bodies that I would expect to see.
Linda - do you see twisted or curled leaves, yellowed foliage, poor plant growth, low plant vigor, or branch dieback?
Also do you see any sticky substance under the infestation?

Please let us know what you see, you are our eyes to solve the mystery.
Thanks

Wooly Aphid
by: Anonymous

I had this on some of my hollies. There is a white bug hides in all this white stuff and when you try to wipe it off there is a white bug that jumps. I called my county agent and was told it was a wooly aphid.
Lilac problem
by: Moni

At first glance I would say you may have a scale insect pest such as mealybug or white peach scale, tho it could be a plant disease...which I am not so familiar with. Usually, scale insects build up over time, tho with the right conditions, populations can "explode". Perhaps they were there before but just recently built up to be seen??
If it is scale insects, you can spray with a summer horticultural oil, per the instructions. This suffocates the insect.
I will continue to look for other possiblities.
Let me know how the oil works.

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