No. A sustained rainfall delivers far more water than any man made sprinkler system could ever hope for.

Powdery mildew is not caused by wet leaves. It's caused by dry soil. The PM is a symptom of that.

I wouldn't worry. Lilacs like clay soil and don't kill easily. Now if I was trying to enjoy a margarita on my lounge chair right there, I might get upset. LOL.

shazam
Powdery mildew is not caused by dry soil. Powdery mildew is a fungus that can live in infected debris in the soil and is spread to the plants when conditions are right.
The conditions are lack of air circulation like in thickly grown plants or plenty of heat and especially humidity.

We have had many years when we have had dry conditions with no humidity and never had an infected plant. Crank up the humidity and there are infections.

Nutsaboutflowers--as long as the humidity is low the lilac will be fine. It takes a lot to kill a one. Powder mildew will not kill it even if it does become affected. Powdery mildew is one of the easiest fungal infections to cure. A good spray with a fungicide will do the trick.

I would be more worried about getting accidentally sprayed when I'm outside

Regarding powdery mildew, oilpainter is exactly correct. In fact the disease is inhibited by free water on the leaves. High humidity (but no liquid water) favors it most.

While I am not completely sold on the idea that the neighbor's sprinklers will not affect the lilac, I will cautiously say there will be no problem. Symptoms of overwatering on lilacs will be limp leaves. BTW, people should not be sprinkling their lawns more than twice a week. While every other day is okay, it encourages shallow root systems, and complete dependency on the automatic system.

The other thing about PM and lilacs is lilacs can often have it and not be compromised at all. In my experience with always having had a lilac hedge, it's just sort of a permanent bloom on the leaves and they are perfectly healthy.

> Powdery mildew is not caused by dry soil. Powdery mildew is a fungus that can live in infected debris in the soil and is spread to the plants when conditions are right.
The conditions are lack of air circulation like in thickly grown plants or plenty of heat and especially humidity.

We have had many years when we have had dry conditions with no humidity and never had an infected plant. Crank up the humidity and there are infections.

--

PM likes hot and dry. PM is easily controlled by spraying your plants with water, as PM hates water. In regards to having a lilac sprayed with water, this does not cause PM.

PM often appears when soil is dry. Yes, it is caused by a fungus. But that fungus is always around. It is only when plants get stressed (such as from lack of water) that PM can take hold.

It is like your stomach. It's full of bacteria and acid. Psychological stress can cause an imbalance of acid that causes the bacteria to flourish and cause ulcers. Back in the "day", treatment was to neutralize the acid. But in fact it was the bacteria that caused the ulcers, and so newer treatments target the bacteria. Or, perhaps the underlying stress.

Well, my poor lilac isn't doing very well these days.

A lot of the leaves are turning brown around the edges.

My neighbour is still watering the heck out of his new lawn. Should I be bold enough to tell him that it's time to cut down on the watering so his new lawn can establish a better root system, and spare my poor lilac?

Are the browning leaves from excessive standing water, or do I have a different problem? The tree has been fine for the past five years, so I'm certain it's excessive water.

What do you think ?

If you are getting standing water around your lilac from the neighbors sprinkler system, I would have a talk with him. Lilacs do not like wet soil. I would think after a month he could begin a more normal watering regime.