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Anna, Teacher, writer, biologist
Category: General
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Should my lilac bush look like this?

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Should my lilac bush look like this? This is the fourth summer since I planted it, and it has been growing well and has blooms in the spring. I didn't do anything different this year. The leaves started turning brown in early July. I don't remember if it has done this in previous summers. Thank you.

I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. My name is XXXXX XXXXX I'm a biologist with many years experience growing shrubs and trees. I'm sorry to hear of your lilac's problem. It definitely shouldn't look like that. Some additional information will be helpful.

Look at the undersides of the leaves that are still green. Do you see any fine webbing? Any very tiny insects?

Do you live in a big city or near a busy street?

In what part of the country do you live?

Thank you.

Hi again,

I don't want you to ahve to wait any longer, so I'm going to go ahead and give you an answer. The additional information may have helped to narrow down the causes, but from your photo, it looks like the lilac is suffering from what is called leaf curl. Leaf curl can be caused by a number of conditions and pests, but when it occurs in mid to late summer or early fall, it is often what is called leaf curl necrosis. it is due to air pollution. Lilacs of all types are very sensitive to air quality. Exhaust from cars on the street, pollutants from nearby factories and power plants, and fumes from lawn chemicals used in the neighborhood, are common causes. Even excessive ozone in the air can cause it. Unfortunately, there isn't anything you can do about this except to give the lilac optimal growing conditions, with the right amount of water and fertilizer. Often, the plant will deteriorate to the point that it dies. If the entire upper part of the lilac is dead (you can tell by scratching off a bit of bark to see if the wood is green or if it is dry and white or brown), new growth may come up from the roots the following spring.

More rarely, insect pests can cause leaf roll, but you should be able to see signs of them. Look for insects themselves and webs on the undersides of leaves. If you find signs of insects, you can treat with an insecticidal soap from a garden center or nursery. If you'd like to have someone examine the leaves to be sure of the diagnosis, I recommend your County Extension Agent. This is a government program through universities, and there is no charge for the service. They won't provide any treatment, but if you take them a sample, they will help with diagnosis. To find your Agent, click on this link, then scroll to your county:

I wish I could give you better news, but I believe you deserve honesty. It's very likely that your lilacs are suffering from leaf roll necrosis. If you have more questions, let me know by clicking on REPLY.


My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back, I am happy to address follow-up questions. Please remember to rate my service only after you have all the information you need. Thank you!

Anna and 53 other General Specialists are ready to help you
Customer: replied 3 years ago.

HI Anna, I'm sorry for the delay in my reply. I'll go take a look and report back. Thank you for the direction. I'll be back!


That's fine. I'll watch for your response.
Customer: replied 3 years ago.

Hello Anna,

I checked the underside and see no "webbing" or signs of insects. Just the general leaf pattern of veins or whatever it's called. They're just turning yellow, then brown, and curling up. I scraped some of the stem with my fingernail and it's moist and green underneath, so that's a good sign, right? I have several other varieties of lilac on my property, some closer to the busy street than this one, and none of the others are doing it. I assume this particular variety might be more susceptible? I don't remember what kind it is. So, what do you suggest I do, if anything, at this point? I don't usually cut it back in the fall, and I just let all the leaves fall off and it's a stick bush for the winter (I'm in zone 7 and it gets very cold and snows). I did fertilize it back in June, and I side dressed it with composted manure. That's something different I did this year that I just thought of. If there is anything I should do now, let me know. Otherwise, I'll go ahead and rate you; you've been helpful.

Thank you. Yes, that variety may simply be more susceptible. sometimes, leaf curl just happens for no obvious reason. As long as the wood is XXXXX, XXXXX't cut it back. Since there are no signs of insects, there isn't a lot you can do. Be sure the shrub is watered during dry spells.You can also fertilize once (now) with an all purpose fertilizer for flowering shrubs. After that, you'll just have to wait and see what happens next spring. I hope the lilac will survive.

Customer: replied 3 years ago.

Thank you, Anna. I appreciate the help. Have a nice day.

You're welcome! Thank you, and enjoy the rest of the weekend.