Lilac disease - what kind and what to do

Quebec, Canada

With this home I have been blessed with blooming bounty, but these blessings are a lot of work and I'm no green thumb. While my attention has been on the wonderful beds on other parts of the property, the lilac bed has been neglected. As you can see in the last photo it's a tangle of shoots and I don't know what. I had been trying to rejuvenate by cutting back a 1/3 every year but that made the shoots go crazy.

This is the third year but I haven't cut anything. So, whatever is the problem, one solution is to cut back, dig out, etc. but what and how I don't know, it's a rather intimidating project to me at the moment.

Anyone know if this is bacterial blight or what?

Thanks y'all!

Thumbnail by teainthegarden
Contra Costa County, CA(Zone 9b)

I agree there is some disease going on, but the only thing around here that attacks lilac is powdery mildew.
If the problem is fungal then spraying the dormant plant can help clean up overwintering spores, then spraying as the leaves open can reduce the effects on the leaves when more spores blow around the neighborhood.
Perhaps bacterial problems can be handled similarly?
Proper ID of the problem is an important first step.

Ayrshire Scotland, United Kingdom

This is also on another thread BUT Diana is correct, all I would add is good hygene with any disease, you must gather up ALL the fallen leaves and burn them, this prevents SOME of thew dormant diseases of fungal infections being able to take hole again the following season, as also said, these are NOT a one off treatment or method of cure, it can take a few seasons to get rid off as the spores can be air-born and you have less control keeping that at bay, but by clearing up the debris and spraying as the new buds break to the size of your tiny finger nail, this gives the chance of the plants recovery preventing it fighting off re-infection again.

Hope everything works out OK as I love Lilac and they are a great plant in any bed / border or even a specimen growing on it's own.

Good luck, hope it all works out for you.
Best Regards.

Lititz, PA(Zone 6b)

It definitely has similar symptoms to a fungal infection. I'd spray it with Daconil. Make sure you spray the tops AND the bottoms of the leaves. You might want to spray it again a week later just to be sure. Also, this spray will not do anything for the leaves that are deformed by the infection. It should kill the current infection and prevent any more leaves from being infected.

Quebec, Canada

Thanks everyone for your advice. I was away for a week and haven't done anything yet. It's such a big deal now I don't even want to think about it much less actually deal with it. I am dreading it, but it must be dealt with...

Quote from WeeNel :
This is also on another thread ...WeeNel.

WeeNel can you direct me to that thread?

Ayrshire Scotland, United Kingdom

Hi teainthegarden, sorry I've been scouring all the latest threads and cant find this other one I mentioned, I know the pictures were like yours, and the problem was about the same. I also feel sure I answered it too. I can only think the thread was dealt with / answered, and then removed, we've supposed to remove threads that are finished with and the writer was satisfied with the results, but MOST folks don't do this and the threads run for months with no one doing anything further with it.

I will keep looking, and maybe someone else will come on board and find the darn thing, IF I do come across it, I will be right back to you.
Best Regards.

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