Forum home Problem solving

Lilac bacterial blight on a very young plant

Hello everybody,

I have reasons to believe that my korean lilac (Syringa meyeri ‘Palibin’) is suffering from lilac bacterial blight. the tree is planted in a protected place on my balcony into a 30x30x30 cm planter and so far it has grown well over the last 6 or 7 months.


I already did research about this disease and I know the affected parts should be carefully cut off, but here is the problem I am facing:


The lilac is a very young plant and specifically this variety is very slow growing and I read somewhere that if I cut any of the branches then it won't bloom blossoms the following year and of course I don't want that to happen.

The second problem is, even if I would cut the contaminated parts off this would mean in my case that I would have to cut the entire branches off leaving the tree with almost no leaves which will probably result in the death of my plant altogether.


So what can I do? Cutting is not really an option since the blight is all over the entire plant.

I would appreciate any advice which can lead to the cure to my lilac tree.


  • BorderlineBorderline Posts: 4,700

    When you say protected, do you mean it is warm? Also, is this shrub grown into an in-set balcony or is it being watered by the rain and opened to light and sunshine? They need sun to flower and they need heat in the summer. I'm trying to work out whether it is growing happily first.

    It is hard to tell from the photos, but classic signs tend to happen around spring time because it's usually due to dampness in spring time and the shrub may have small damage that can be an area where Blight starts. How was the flowering this year? If Blight had taken hold, the flowering is quite affected and you will see shrivelled flowers or blackened ends.

    I also think your pot is a little crowded. I know it is a slow growing shrub, but crowding the base (some other plant growing there) and causing congestion will stress your shrub and it will be susceptible to Blight and other fungal diseases.

    The shrub likes to grow from neutral to alkaline soils and do not feed them high nitrogen feeds. Over feeding can also cause problems. If you don't want to take action now, then wait till spring next year to see how it grows. If you see shrivelled growth or blackened leaves, then you will need to spray a copper fungicide spray straight away.

    Long term, inspect your branches and prune off damaged branches, also try to thin out so it is not so dense, which can also encourage the problem.

    Last edited: 20 September 2017 20:33:25

  • Thank you for respondin, I will try to answer your questions.

    With protected I meant there is only one opening, it is a capsule balcony with south side open the rest is closed with glass like a winter garden but there is always enough air everywhere because the weather is usually very windy around my place.

    Since it is south east located there is full sun when sun is shining, so depend on weather condition, but also it is very light so even when it is cloudy weather the balcony is always having bright light since it is painted with white walls and plenty of glass work around.

    Can’t say about the flowering because I bought the plant this year in may and since then it had only green leaves, no flowering yet so I am hoping for next year because the flowering time I have been told is around April / May.

    The ground creeping plants I removed months ago while the lilac was still ok, the blight has occurred much later, however I did gave it some nitrogen fertiliser so perhaps this was a big mistake :(

    I placed the planter towards the open side of the balcony so yes, when rain falls it gets a little bit of it. But there are 5 holes in the planter bottom so there is no water clogging happening at no time. 

    I have treated the lilac 2 month ago with a fungicide and a pesticide because I have other plants that needed spraying and when I spray I usually spay all of them to minimise the chance that pests are jumping from one plant to the other.

    I am very scared about pruning because I read somewhere if I prune this tree it will not flower next year, luckily since this tree is very young, there is not to much density yet, so all branches are having freedom and space.

    I will look for a copper-fungicide since the other fungicide I sprayed earlier this year was a fungicide without copper I think.

    If needed I can take another picture tomorrow in daylight to provide better material for assessment. Thank you so much for your help.

    Last edited: 20 September 2017 20:56:17

  • BorderlineBorderline Posts: 4,700

    Thanks for the information. The balcony surrounded by glass can be hot and also humid if you have a lot of other plants too. Good air-flow is needed right now, so you need to keep it much more in the open area with no canopy.

    I don't recommend you spray your plants whilst you are treating other nearby plants, especially if there was nothing wrong at the time.  The best thing for the shrub is potting into a loam based compost and into a larger sized tub. 

    No need to prune now if you are still unsure. Don't feed for now and just water the plant if no rain water on it for more than a week. They always need steady watering throughout the year because they are not in the ground and the smaller the pot, the quicker water will be absorbed or lost, so keep an eye on the watering. Any stress like that can cause issues. 

    Based on the second post, it's not necessarily Blight as you have not seen flowers as such and I saw one and it looked fine. In fact, your leaves looked a bit like either chemical damage or wind scorch. The leaves will drop off eventually, so let's hope next year, the new leaves are not distorted and you see flowers in late spring.

  • This is a big relief, I am feeling much better now. I always expect the worst and so I diagnosed blight but to be honest I have no clue. Now that you mentioned wind scorch I think it could be exactly that because indeed it has been some hefty winds lately and since the tree is standing right below the open part of the balcony it always receives the heavy winds that blows in.

    Just out of curiosity.... you mentioned the word shrub. I am a bit confused, as I was thinking a shrub is something that grows out of the ground directly but the lilac plant I have has been fixed on a high stem and the seller told me it is a standard tree version. So is it a tree or is it just a „shrub on a stick“? image

  • BorderlineBorderline Posts: 4,700

    Yes, I mention shrub without thinking...I can see your one may be a carefully pruned 'standard', or possibly has a different root with your Lilac grafted on the top. Lilacs are shrubs or trees depending on shape of it, but I guess, naturally, without any control, they grow more like a shrub.

  • I wanted to say that but I forgot that term, but yes it’s is a grafted one, not just pruned. 

    You have given me new hopes, now that I think it is not blight but rather wind scorch, I will just wait to next year and hope for the best. Thank you very much. image

  • BorderlineBorderline Posts: 4,700

    Good luck for next year! 

Sign In or Register to comment.