Inspect the lime-green grass, looking for whitish stems that crawl along the surface of the soil, and the grass acting "floppy" instead of upright. That stuff in the pictures is exhibiting many of the characteristics of Poa Trivialias, a troublesome and difficult-to-eradicate grassy weed.

thanks guys thats really odd if it is that type of grassy weed. i never had any signs of this until i planted new grass. in fact, the grass on the bottom of the picture is a 2 foot wide strip about 30 feet long that is next to my driveway. its all new grass and has a nice dark green look to it.. i used pennington sun and shade smart seed for that.

then i went around the yard looking for bare spots and planted grass seed around there too. i thought it might be because i fertilized too much or just because the grass is newer. would new grass or overfertilization give the same light green appearance as the poa? i dont understand why it would suddenly pop up in the yard now only after i planted new grass seed.

the other reason i think this is because the lighter lime green grass is only popping up where i fixed bare spots, which for me might indicate its just immature grass. im going to examine the grass leaves tomorrow to see but i guess my question is can immature grass you just planted have this lime green color as well? i think its all over my yard because i did a ton of barespot fixes.

That's why I mentioned the telltale white stems (stolons, really) of Triv as a diagnostic tool.

Poa Trivialis has become a real contaminant of lawn seed, and is not listed as a weed seed or crop seed on the seed label. On another forum, I have overseen tons of renovations, and Poa Triv following renovation or overseeding has become a major problem - we now recommend buying certified "sod quality" seed online to avoid the problem.

thanks andy. i went out and checked the lawn and didn't see any white stems but then again i dont know exactly what im looking for. i could take a really close up picture if that would help. i looked around the internet looking for examples of the poa trivialias but only found the bright green look of it. do you have an example of what the white stems look like? from what i've read this stuff is really hard to kill too like you said. if it is trivialias im not sure what to do about it

The stolons/stems Andy speaks of are "runners" originating from the original plant that grow along the top of the soil and at their end they root to produce a "daughter" plant. If you drag your fingers like a rake through the turf, your fingers may catch on them, then spread the leaves and take a closer look. I have never seen an actual photo of them on the net. If you google "turf grass structure images", you will find drawings that depict stolons.

Bright Green, Reed-Like Grass, fast growing. Stiff.

Looks like Nutsedge.
Ortho Makes spray.
Grows in wetter Grass areas,
I'm in Zone 4 Minnesota
Spray works but may kill surrounding Grass.

Lil Sunfish Linda@mightyagent.com

Tenacity is quite effective on nutsedge without damaging surrounding grasses (although they may bleach a bit for a month or so).

Repeated apps will also control P. annua and P. trivialis, but it's not completely reliable. Still, I've had great luck with it.