Grubs caught red-handed (so to speak) eating the roots out from underneath a patch of grass.Q: I was out working on the lawn over the weekend and realized that some green grass patches were pulling up. Boy, do I have grubs! I'd say 10-15 per square foot. Although the grass is green, I decided I should pull it up as long as I was finding grubs, thinking that the grubs were going to kill it anyway. Before I get too carried away, should I continue pulling until I've removed all the grub-infested sod? Or should I stop and only resume if it eventually turns brown?
A: That's a grubfest, all right. Ten to 15 of these root-munchers per square foot is definitely enough to do serious lawn damage and warrant treating.
Before pulling up any more green grass, I'd go with a quick-kill grub treatment -- a lawn insecticide containing either Sevin (carbaryl) or Dylox (trichlorfon). Water it in after applying.
Those products should stop any more damage within days. That should give at least some of your green grass a chance to recover and reroot. In other words, if it's not already dead and brown, you may have enough uneaten roots that the lawn will end up coming back faster than if you started from scratch with new seed.
Grass that's not going to make it will eventually brown out. That'll be apparent next spring when the grass starts growing again and you can see what made it and what didn't. That's still a decent time to pull off and patch dead areas. The only drawback of that is you would've had an earlier recovery by reseeding in fall.
I'm not a big fan of lawn chemicals, so what I do sometimes -- even when I know I have grubs down there feeding -- is patch anything that browns in the fall and then go back and patch whatever else they finished off in spring. It's extra work and a lot more reseeding than if I'd just have killed them, but I've got a well and would rather patch dead grass than wonder if anything harmful got into my drinking water.