Lilacs can be very susceptible to "weed" killers so it is difficult to predict what might happen here. I have seen Lilacs growth inhibited because "weed" killers were sprayed around them. This will be a wait and see since you did what was appropriate at the time.

kimmq is kimmsr

I'm confused, you were going to spray but the neighbor beat you to it? Why were there such big weeds around the lilac? Was it sprayed on the foliage, or just around the base (if you know?)

Pulling is the best solution to weeds, as soon as they sprout, before they have dropped another crop of seeds to come up again next year, not packages of stuff from a store after weeds are so big that a neighbor might notice. Pulling them much sooner can break the cycle, so they don't show up again next year.

Regardless, your neighbor shouldn't be trespassing &/or applying sprays to your yard, no doubt!

If you're able to add a pic of the spot in question, the feedback could be more specific, with hopefully some solutions to the overall situation.

I would seriously consider installing a privacy fence between you and this new neighbor. He sounds like constant trouble in years to come.

I don't have big weeds. And I have been pulling them out but they are getting wY ahead of me. He has big weeds and almost no grass. But when I checked out the lilac bush after he ran into the house, the ground was wet with his spray as were the bottom leaves and all around the bush including under the bush. He sprayed right into it. My front yard looks much better. This is the side where I planted new grass that is coming up with the weeds looking toward his house. The tall weeds are in his yard.

Some of the lower leaves and new shoots are turning yellow. :(.

please show us the yellowing. Could have causes other than weed killers.

How are the lilacs looking?

I'm not certain what will happen to the bush. Part of it has green leaves and was not affected by the weed killer. I water it well every day. Any suggestions? Other than a fence?

If it didn't lose all it leaves immediately, it should be okay (allowing for the winter). Watering it, as you did, will help immensely. You may lose a couple of the suckers, but lilacs are tougher than they look, and you may be pleasantly surprised in the spring. A fence is definitely in order, with a neighbor like that.

TY for the update! Definitely still alive! Washing it off right away probably helped a lot. This should be inspirational, encouraging for whoever else might read this, from a similar situation. Accidental & "neighbor sprays" are pretty common.

Putting a little mulch &/or compost around the base (but not touching trunks) is usually appreciated by any plant that's tall enough. Helps to moderate soil temp & moisture, increase fertility. A cute little border of bricks or whatever you'd like to look at can help keep grass from creeping in, mow with chute aimed away from bed areas.

Doubtful these need water every day. I'd stop doing that unless it doesn't rain for a week or so or you see wilting. Too much water can make plants ill. Assuming they're still alive next year, shouldn't need to be watered unless it doesn't rain for more than 2-3 weeks during really hot weather.

Good luck, lilacs!

About 20 years ago a friend, contrary to my advice, sprayed 2,4,D around, not on, a very large Lilac and saw it die off some but kind of come back. What once was a Lilac over 6 feet high that blossomed very prolifically is now a Lilac less than 4 feet tall that blossoms fairly well most years.

Lilacs are very susceptible to "weed" killers of any kind.

kimmq is kimmsr

Your neighbor is a bully, a coward, and a thief. I bet if you weren't a woman, he'd never have set foot on your property.

My neighbor killed off my 3 huge lilacs and tree. They had ferns from my parents house under them. He didn’t like ferns or hostas. Now all of the sudden it’s all dead. After 30 years of living here, just magically have no blooms, dying branches, and NO ferns. I pull weeds by hand, I don’t use Roundup. I’m so furious. These shrubs were put in around 1979 and were huge and healthy.

My lilac bush I posted about totally died. Baby shoots try to get started, but the bunnies eat them. I bought wire waste baskets to cover them and see if they grow.

The bush was planted in memory of a child who died.

I'm sorry to hear that, Linda.

Is that neighbour still there? Horrid man - I think a barbed wire fence and a large, salivating dog are the order of the day.

Thankfully the arrogant dumb young neighbor moved away and nice people moved inin.