It could be poa triv, poa annua. or some other weed. I would lean toward annua, since it produces tons of seeds at very low heights and it's everywhere. Poa triv needs to grow to at least 7 inches to produce seeds, and they aren't very prolific seed producers. A picture of it would be worth, well, a thousand words. Yards don't reseed themselves unless you don't mow your grass for a whole season, and spreading grasses like KBG spread slowly and it would be next to grass that is established. Most grasses do start off lighter than they will be when mature.

I'm curious - I've read that one should apply Certainty in late fall. However - you seem to have applied it in the spring - any thoughts on that? I had such a problem I would've used Roundup if Certainty weren't available. As it happens, I later decided to reseed with elite bluegrass, so I could've saved some cash and gone with the Roundup to begin with. You live, you learn. It worked just fine--with no bluegrass burnout that I could see. I don't know if a fall app would've worked "better," although better in this case would have been a 100% kill instead of 99%. Somehow that doesn't concern me much. One more question: in your pics (the yard looks awesome, btw!) - you have a picture labeled as "Invader1", etc... Have you identified this "invader"? I have something similar. Does it grow in a star formation? I have a blend of KBG, p. rye and creeping fescue - these patches of this grass stand out like sore thumbs. It seems like perhaps a warm-season grass - almost like a finer-bladed crab grass... Thanks! I just mulched the newest garden bed today (the last, I think--a third of the property is now gardens and there is no remaining lawn against the house at all). The Invader1 and Invader2 images were what people identified as Poa trivialis. It was just very mature triv... Even if it weren't triv (I'm pretty sure it was), the Certainty took it down.

yes...more simply put I was asking if you had a roll bar of sorts on your mower or if the grass naturally leans over. I did get my height down to around 1.5in before overseeding but the rest of the turf has really taken off from all the watering I've done. I'd rather wait as long as possible considering that I checked the new seedlings and although they are roughly 1-2in tall, they pull right up when I applied just a slight amount of "tug" to them. As for the rest of the lawn (the original sod was laid last spring), the blades are nearing 4in. I did purchase a reel mower which I've read helps reduce damage to seedlings but the reel mower did not come with a bag attachment and the longer I wait, the more thatch I could create with the clippings. The mower I bought also only adjusted to a max 2.25in. (the only one I could find was a "task force" reel mower and I actually plan on returning it once I'm done as I've heard these aren't the best long term) Just feels as though I'm in a catch 22 here. How do you post pics on this forum? I tried with my initial thread but typing out the image brackets b/w my url but it didn't work ( [img][/img] )

Tenacity can help here, and it doesn't kill your (northern, which I assume it is) lawn. Although several sprays may be necessary to finally control it, and you do have to keep after it (it'll keep coming back for a number of years), eventually you do finally get rid of the stuff.