What is this on my lilac bush???

Looks like a type of fungus....I would like to spray it with something....but I am not sure what...before I purchase a fungus spray I thought I would ask the experts......any and all suggestions are greatly appreciated....

I don't know what it is, but it seems to be pretty common on lilacs...i have it on mine. Doesn't seem to hurt them any, but might just be result of a single observation.

There are some shriveled up leaves on the bush as well as on the ground....it was like that end of the summer last year and I did spray a "Fungus" spray on it....Ortho I believe....I just don't wanna loose it because it is pretty large...my others have just a "touch" of it on them but not as bad and no shriveled up leaves....

Looks like Powdery Mildew. Lilacs are very susceptible, but it hits many other plants too. My lilacs had it bad last year, this year no sign of it at all. I didn't do anything to them. http://gardening.about.com/od/gardenproblems/a/PowderyMildew.htm Or just google it. Not a dire problem, you lilacs will likely be just fine.

I would have guessed powdery mildew as well. I have had it on mine before, but they are normally very healthy anyway

Get a spray bottle and put in a couple drops of dawn dishwashing soap and coat everything and see if this helps... it's been a wet year and mildew is common this year

We have powdery mildew starting on our plants in the garden. I found a recipe for 1 quart water, 1 tsp baking soda, a few drops of hand soap and a tsp of vegetable oil. I've sprayed and the plants are looking better. It says to spray 2 times a week if rain, and once a week if it's dry. It will raise the ph to help prevent mildew. Some plants the mildew won't hurt.

Mine get this sometimes too, as do the magnolias. They don't seem to be harmed much. Fungicides are one of the possible causes of the decline in honey bees, so I'm not a big fan of that route.

I see that on my lilacs as well . . . no harm, no foul in leaving it be.

+1

Yep, PM or downy mildew for sure. Anti-fungals, some of the friut tree sprays work well, otherwise look for anti-fungals. I respectfully disagree with 'no harm', as a competition pumpkin grower, PM is to be avoided but is often unavoidable. It taxes the plant and will eventually kill it, with Lilacs they typically go dormant before they end up dying so the cycle starts up again the next year. If you want to go non-chemical, a dilute mix of milk (yes, milk!) around 10-20% sprayed once a week throughout the season tends to delay infection but not cure. When treating, make sure all leaf surfaces are treated, sprays often are hit and miss unless you take some care. Funny story pumpkin wise, my neigbors have Lilacs on the edge of our yard, and I monitor these plants throughout the year as my PM indicators. When they get infected (they always do eventually, PM is typically late season), I up my treatment on of the pumpkins. Last year they had one plant that was always covered with PM and was my test bed, the others right next to it did not get it as bad at all, never did figure out why. That plant is now a gap in the hedge as it did not make it this year, PM is very tough to treat thus the 'delay' treatments such as milk tend to be the best route. You can buy PM resistant plants too.

Czech- it's definitely more of an effect on punkins/squash etc.