It's time to vote on our 2017 photo contest! Vote for your favorite photos of the year here!

what's Wrong With My Lilac?

southampton, United Kingdom

Every year about this time the leaves on my lilac start to go brown(see photo) I was told to mulch every year with my homemade compost,which I have done for the last 4years,but it makes no difference. Please help

Thumbnail by smurfy
Cedar Falls, IA(Zone 4b)

Can you provide some more information. For instance, does it start out as spots, does it start out as yellow or go right to the brown we see? What are the soil (pH & type), sun, and moisture conditions it is in? Do you have other lilacs, or do neighbors, and do they have the same problems or is it just this specimen? How does the underside of the leaf look.

There are a number of potential problems, and first thing to rule out is that the plant is just not in a good location to thrive. If it is not, you'll keep having problems. Generally, lilacs do best in full sun, or very light shade, and with neutral to alkaline soil. They don't like too much heat, but given your locale that shouldn't be a problem.

One possibility, which produces yellowing and browning between the veins in some plants is exposure to sulfur dioxide pollution. If you know of a possible source of sulfur dioxide nearby, that might be a problem. A power plant or factory that burns coal, or a major highway are two such sources. I haven't heard of lilacs being particularly susceptible to this, but it is worth ruling out.

There are several possible disease problems from bacteria to fungal diseases. There could also be problems with the roots that could show up in the leaves.

You also mentioned that this happens at the same time each year. It could also be that you get a lot of rain or little rain at this time of year, that could contribute to the problem by setting up the conditions for a fungal attack or stress the plant to make it more susceptible to disease. If you can't remember back to past years, has there been a particularly wet or dry spell recently?

Ayrshire Scotland, United Kingdom

Hi Smurfy, where you live, cant see it being a water shortage, and the dressing of compost is great, so looking closer at your pic of the leaf, I would be going in the direction of a grub called leaf minner, this little bug/moth flies in, then lays it's eggs on the plant and the baby's (pupa) gets into the leafs and stays there till it is of age to flee off and do the cycle all over again, being inside the leaf, means that other things like bird etc, cant feed on the little babies as they cant find them, you ofcource see only the evidence, to make sure this is what I suspect, take a leaf off the bush, go indoors and tear the leaf down one of the brown mottled bits and try to seperate the tissue like taking apart a sheet of tissue hankie, you should find the tiny little grub/catterpiller, in between the layer, then squash it. to treat this problem if thats what it is, when the lilac leaf miners (MOTH) is active, normally about end May early June, get a spray from the garden center and start to spray your Lilac shrubs to try deter them from laying the grubs inside the leaves,and to kill the moths before they actually do the damage, this bug very rarely kills a shrub, however, it really is more unsightly, a real bad infection can cause all the leaves to fall off and defoliate the whole plant, but the next year, the plant normally makes new leaves, the other thing to help, as soon as you seee the brown telltale signs is to pull off the brown leaves, but really trying to spray before or as soon as you find the first markings in early spring is the best way, there are lots of moths that do this to different plants and all are different moths, so you wont have this problem all over your garden, there will be lots of different remedies on the market now that are not chemicals, but best to ask at your plant store for what would be good, it's the timeing of the spraying that will give the best results. as for now, just try remove all the brown leaves and burn them, even leaves that are on the soil, so next years moth population is reduced in your garden.Good luck. WeeNel.

southampton, United Kingdom

Thanx for your replies,
yes it goes straight brown, the pic was the underside of the leaf,I will put a pic of the topside with this post,soil neutral to alkaline 7-8, it gets sun from about 12noon onwards,wev'e had lots of rain this summer but a very warm spring, every year has been different but the browning of the leaves has been the same
There are no factories etc nearby and my neighbours across the road have a lilac with no problems
Iv'e looked to see if there are any insects but there are'nt any

Thumbnail by smurfy
Ayrshire Scotland, United Kingdom

Maybe the little catterpillers have already turned into moths and left if you tear the brown bit of the leaf apart and the brown space is empty/hollow, you deffinately have an insect that has tunneled it's way in, because you neighbour dont have it, it dont meen to say she would get the grub anyway, she lives in the same seasonal conditions as you, so you would expect them to be affected by the same growing conditions, ie, rain fog, fungus etc, I still feel you have had the Lilac leaf tunnel moth, but another pic would be helpfull to try solve your problem. good luck, Weenel.

Mays Landing, NJ(Zone 7a)

I think WeeNel is pointed in the right direction. Timely, preventative spraying next year could make all the difference.

southampton, United Kingdom

Hi All
Thanx for all your advice, I did look again at the brown patches but there were no signs of hollows where any insects might have been but I will spray next year to see if that makes any difference,by the way I forgot to say that it is a standard lilac,not a bush although I don't suppose that would make any difference.
Anyway, thanx again for all your advice

Ayrshire Scotland, United Kingdom

Hi Smurfy, no it wont make any difference to a standard/bush/tree, they all get the same problems, is it getting enough water/air circulation and feed etc, I always give mine a feed at the end of the season and again come spring just as the sap starts to rise to make the leaf start to open, I also deadhead the flowers so they dont use energy making seeds which I dont want it to do, hope you find the cause soon as these are lovely plants, Good luck. WeeNel.

southampton, United Kingdom

Hi WeeNel,
thanx for your advice,I'm posting another pic as you asked for in an earlier post,this is a pic of the leaf in the early stages I don't know if it helps any,the lilac has still got some unafected leaves on it but as they mature this is what happens to them
It is by a fence but most of the leaves are above it so I wouldn.t think it was air circulation and as for watering no one could have had more rain than we have in Britain this year so I don't think either of those things could be a factor.
Maybe just putting my own compost on it is not enough,so I will take your advice and feed it.
which feed would you recommend? Someone suggested growmore
Anyway thanx for your help much appreciated

Thumbnail by smurfy
Ayrshire Scotland, United Kingdom

Hi Smurfy, at last I have got to the thread, I have searched the Encyclopaedia that I have to try resolve the leaf problems on your Lilac, so I will give you what it says in brief.
Browning or the leaves
Lilac blight: Causes small angular Brown spots on the leaves and young shoots blacken and and wither away. Dont recognise that from your discription so feel we can ignore this.

Physiological Disorder: Caused by adverse soil conditions, shows as discolouration of the foliage, premature leaf drop, ie, before the season ends and normal leaf fall time,
The most common trouble occurs in mid summer, when the leaves may become brittle and curved , they first show yellowing followed by brown blotching, this is associated with Magnesium defficiency.

Looks like maybe that could be the clue, it is worth a try anyway as it wont do any harm to the Lilac in any way unless you over do the feed, just follow the makers directions as to how much to use.
I really cant give you the name of feeds that will give the Mabnesium mix you will require, but if you go along to the garden center and read the labels on the feeds or ask an assistant who can tell you the best one to try, then I would give it a go, quickest results will be seen with a liquide feed or foller feed, but after that, you may need to keep useing it, so make that a quick fix and then to the soil add one that is soluable and added to the soil around the roots so the plant can get this over a longer period, wish I could see the bush myself to help you further, but lets hope this will help, remember, no feed works instantly, and the leaves that are damaged wont get green this year, maybe nip them off in fact, but what you want to try do is feed for the longer term, so next year when the leaves come, they will be healthy and stay blemmish free with good flowers, as a standard bush is always grafted for lilacs, usually onto a privet root/stem I dont think that part will be the problem, but early next year, it should be monitored from the first burst of foliage to get any probs cought as soon as you first see signs and it can be dealt with before ALL the leaves are browning, Hope this will be the right way to go, keep in touch and lets know how it goes. good luck. Weenel.

southampton, United Kingdom

Hi WeeNel
Thanks for all your help I will follow your advice and let you know how it goes next year
Thanx again

Ayrshire Scotland, United Kingdom

Smurfy, no trouble at all, just hope this is the right way to go at last, really cant think of anything else for the time being, but if anything does comes to mind, I will be back to you, dont think anything more can happen to the bush this year as any damage has already taken place, so for now, it is just a case of get the soil fixed with the right neutrients, so you will know early next year if the problem has happened again and you catch it earlier, incase though that it should be a fungus, remember to gather all the fallen leaves in the autumn and deadhead the flowers so you get a clean start for next spring. good luck, hope we have manages to help, pic next year to us will soon tell the truth eh. WeeNel.

Boulder, CO

Hey thanks you folks. Here in Colorado, USA am having the same sort of problem with some Lilacs. As I looked a little more, I'm starting to think it may be something called Phytophthora dieback. And a search of that sends us back across the ocean to:

Drainage maybe an issue, too.Yikes, eh?

wichita, United States

Hi. I have a new lilac bush & I have had it a month or two. In one day some of the leaves turned brown, brittle & turned up on the sides. We have had a lot of rain up until last week. It has turned really hot, mid 90's. My plant sets on the west side of our house & it gets sun all afternoon, with no shade at all. I have a lilac in the back yard I have had for at least 6 yrs & never a problem, but it sets on the back of the house facing south with lots of big silver maple trees that keeps the yard cool. I have fertilized it twice with Miracle Grow liquid feeder. I have plenty of mulch & it has good drainage. I don't know what the ph of the soil is, it's good dirt, old wheat fields some 30 yrs ago. So any ideas would be appreciated. I'm considering cutting the plant back maybe a 1/3 to 1/2, so it doesn't pull the whole plant down the tubes. Thanks-Squigums

Bolingbrook, IL(Zone 5a)

I have a lilac that is not growing very well and has a whiteish look on its leaves. As a precaution I have put a large plastic over it and closed it as titie as I can in case it is contagious. Any ideas?

(Zone 7a)

Yours might have powdery mildew. Lilacs are prone to that. Covering it in plastic is not really a good idea, as far as I can see.

Post a Reply to this Thread

Please or sign up to post.