Forum home Problem solving

unwell lilac tree

the leaves on our lilac tree have dark blotches and are curling up and the trunk has a pale green powdery substance on it, any help would be appreciated, many thanks



  • the trunk photos look like a fungal infection possibly, the leaf pics look like a mineral deficiency, but I would bet its a fungal problem, I have no idea what sort though

  • thanks treehugger80, I've looked up lilac diseases but not seen a fungal infection of this pale green colour anywhere, there are several lilacs there and this is the oldest so would hate to lose it, there was a clematis growing through it that looked to have clematis wilt and I have cut it down so hope that hasn't caused this problem, I've inherited the garden from my father and I'm very much in the amateur stage at the moment so appreciate any help image

  • BorderlineBorderline Posts: 4,687

    How was the flowering this year? Problems with Lilacs can show up early in spring time where flowering can be affected. Flowers may be less abundant or even shrivelling up.

    Powdery Mildew can show later in the year and can be a common problem on congested plants. Make sure there is adequate air flow around the area. Damp wet weathers and maybe your Clematis sitting around it has made it more dense, but they will recover from that. 

    Check your branches to see if there are damaged or diseased looking areas. It's through these areas bacterial blight can take hold, and in time show up with leaves that are deformed and black, a bit like the ones in your photos. 

    If you have not seen any damaged bark then as a precautionary measure, collect all dead and fallen leaves immediately, and don't leave them sitting there over the winter months. To be on the safe side, don't compost the leaves either. Scrape away the top layer of the soil surrounding the area and lay new mulch. Start to thin away a few branches that may be too dense. The shrub may just need a good tidy up and checking which is usually a prune. 

    Last edited: 22 September 2017 17:23:42

  • image thanks borderline, this was the lilac in April maybe not as many flowers this year as usual but was looking healthy then, I'll check for damage etc a follow your suggestions so fingers X'd ?

  • BorderlineBorderline Posts: 4,687

    Thanks for sending a photograph of your Lilac for this year's flowers. I can definitely see some dead branches there already. Pretty mature and will need managing. In that, I mean thinning and even cutting some stems almost down to the ground. This helps by keeping it less dense and also having fresh stems on your bush which is vital in Lilacs for flowers and the leaves. Any pruning or hard pruning now will mean you are cutting off next year's flowers. The best time to prune them is after they have flowered, and for you this needs to be done every year because it looks like it's reached around 5-6ft tall. From that height, if you don't prune, they will start to not perform as well.

  • thanks for that, I did do some pruning after this year's flowering but obviously not enough, so will thin out more next year, it's actually about 10-12 ft high now so I've got my work cut out next year ?

Sign In or Register to comment.