Couple questions and I'm not an expert.
1. Picture?
2. What weed killer?
3. Does he have irrigation?
4. It's taken 2 months for his yard to die?
5. Does water run from your yard to his?
Sorry for the bombardment of questions, just trying to get a feel.
Josh

I think HE should get a soil test if he's suspicious. The guy's yard has a problem and he blames his neighbor and just expects you to pay up?

You used a weed killer that does not kill grass.
The TARGETED area of this chemical is growing grass, so how could a peripheral area be worse?
How does he know you used that stuff in the first place?

Sorry, but it sounds like your neighbor is full of fertilizer.

15 feet into his property????? HE needs to prove that. You do not need to disprove it. There is nothing you can spray where the overspray will wipe out at a distance of 15 feet. If you get 3 inches of overspray death, then sure. 15 feet is freakin nuts!

What was the main ingredient of the spray? Unfortunately the most popular weed killer is glyphosate and that happens to be a grass killer, too. If you use ANYTHING else, he has no leg to stand on. He has insects or a fungus. He probably has a fungus if it happened very quickly and is targeted to one area.

Pictures would be very helpful.

It is doubtful you did any harm, but not out of the question. Do you know what grass type your neighbor has? Some grass types like Saint Augustine and Centipede are very sensitive to weed killers because they are basically what weed killers target.

Also if you have Saint Augustine and used Atrazine, and your neighbor has Fescue, Atrazine will kill Fescue, Rye, Blue Grasses, Bermuda, and Zoysia.

Personally I wouldn't worry about it and tell him to jump in the lake. Only if he serves you papers in small claims would I pay. Otherwise fences make for good neighbors.

a good relationship with a next door neighbor is valuable. people are more important than being right. see if you can salvage the relationship. if you live there a long time, you will thank yourself.

why not ask him if you can try your hand at rehabbing his lawn? tell him you're learning about lawn care, and although you don't think you killed his grass, you'd be more than happy to try to help rebuild his lawn to get it healthier than ever. ask him if he wants to tackle it together. you might end up working togther on it, which could forge a good relationship.

trust me, a good friend in the neighborhood is worth more than being right. when you're out of town, locked out of your house, or out of milk, you want a friend next door. i've learned from experience.

WeedBgone w/crabgrass contol will kill clover. 15' doubtful. Put him in touch with ruthie so she can write him a check. Otherwise I'm with TW--tell him to kiss you where the grass don't grow.

heyruthie:

I would consider myself to be very fortunate if I could have you as my neighbor. I'm sure your neighbors feel that same way about you. I appreciate the perspective you shared in your post. Thank you for sharing.

Your neighbor sounds like a d-bag, for lack of a better term.

Thanks to everyone who responded!

Here's a picture. My lawn on the right, his on the left.
Keep in mind that I sprayed EVERYWHERE on my lawn on a day that wasn't windy (I made sure)over two months ago. My weeds died within a week and his stuff was still very green.

My grass is very green and I actually have weeds growing back in all the areas I sprayed.

He also said that he had tried fertilizing his lawn to get the yellow to stop. It does seem like over the last two week it got very yellow, very quickly.

Another thing: Do you see the "island" in his yard? Yesterday, two of his plants were very wilted and his gardener cut off the top of them. I think that if my weedkiller was going to kill of his plants, it would have died at the same time.

We don't share irrigation. He has his own sprinklers and I have mine.

Here's what I used. http://www.homedepot.com/buy/outdoors-garden-center-lawn-plant-care-lawn-weed-control-grass-weed-killer/ortho-32-oz-concentrate-weed-b-gon-max-plus-crabgrass-control-133197.html#.UBwtgU1mRyA

I believe that our grasses are different. His has clovers and these tiny blue flowers growing throughout it. And, literally, the week I moved in he was talking to me about redoing our yards together.

I actually really like the guy but I just don't feel like it did this. The fact that his grass AND plants are dying two months later? I just don't think the chemicals would stay in his yard and not mine.

Right and left of what? Everything to the right of the island and above the botom stake/water head appears dead or dormant. Maybe I owe ruthie an apology.

Left of the sprinklers is his yard. You can see my grass in the bottom of the pic is healthy and green. I sprayed every inch of my yard and everything is healthy. Even my bushes are alive and kicking

The lawn to the right, my lawn, is actually not grass. It's a dormant native tall (like 6 ft) grass that the previous owners let infest everywhere. Come winter time, it'll grow up green.

It looks worse than it is.

Now that you have given more information and a picture, it would appear that the material you applied had nothing to do with the decline of his yard. Perhaps he should be asking his gardener questions for the answers to his issues.

Does your lawn slope down toward his lawn, or vice versa, or are they about level with each other? Herbicides do not normally move uphill.

Thanks again for responding.

The yards are level with each other and slope towards the picture's perspective (to the street).

I am going to offer to help out with the rehabilitation (per ruthie's advice) but not take responsibility for what happened.

We'll see how he takes it.

If I had seen the picture without the story I would say one of the sprinkler heads wasnt working,

No need to pay for the materials since you're offering to help fix the problem.

Honestly, I think this is one of those situations in which it's impossible to tell what happened to his grass. It could have been killed/compromised by any number of things. I doubt it was your doing from what you've said. The important thing is that it's going to get fixed and he'll have a nice new lawn and someone he can ask for advice in the future.