There shouldn't be any interaction. You might want to rethink your choice of herbicides in the future though. Sevin is one of the most toxic products you are going to find available for lawn use. It is pretty nasty stuff - at least compared to some of the other options.

I hear you, bill.

But in my neck of the woods (Ontario, Canada), Sevin is pretty much the only game in town to control chinch bugs, webworms and grubs. Virtually all of the attach-and-spray and concentrates for common lawn pests are 22.5% carbaryl (diluted to about 5%).

On that note, it's pretty funny shopping for this stuff. The Canadian arm of Scotts packages different versions of Bug-B-Gone Max: one for grubs and another for ant & chinch bugs. The labels are different but what's in the bottle is the same: 22.5% carbaryl!

If anyone knows of environmentally friendlier pesticides in Canada for chinch, grubs and/or sod webmorms (yup, I've had all three), please let me know.

I know Sevin can be used to thin fruits on trees.

If you do a web search is several studies come up which say 'excessive' amounts affect grass seed germination. I didn't see where 'excessive" was defined.

Sevin is the most toxic pesticide that we buy at the stores...

at least 90% kill on earthworm population...

Kills everything including the beneficial ones. Maybe that's why I never see toads anymore???? I don't see lizards anymore either.

I just let nature take over... that means beneficial nematodes which controls hundreds of bugs without harming the beneficial ones.... Let spiders catch those annoying grasshoppers and japanese beetles which is pretty damn cool to see in action. Birds come and go but they get some of the bugs. It goes on and on...