thanks. pic #2 and #3 are actually of same grass in same area but lighting affected color. Both grasses send runners out underground very similar to bermuda grass that I experienced where I used to live but doesn't seem AS aggressive as bermuda grass but you can get long strands with "tentacles" on them as you dig into the soil and dig them up. The runners I've seen are usually short but I've seen as long as perhaps 6". Does that give further insight? The description for orchardgrass didn't make mention of runners so I wanted to provide this additional info.

It does look like you need to be mowing weekly, at least now while it's raining a lot. When it gets hotter you might not need to. There is an organic pre-emergent (blocks seed sprouting but does not kill anything) called corn gluten meal that you could try. It is a nitrogen fertilizer but it does not have as much nitrogen as chemical fertilizer and it is released more slowly into the lawn. I used to buy it at a cattle feed store (it is a protein additive that is used in lots of pet and cattle foods) and it was not too expensive when sold as feed. The kind that is sold as fertilizer is a lot more expensive. I had really good luck with it but I did have a spreader that would dump more than it was supposed to, so I spread it pretty heavily compared to instructions--about 50 pounds over 2000 sq ft or so. Anyway, my lawn looked really good when I used it, better than any chemicals I have tried. But like I said, it doesn't kill weeds, it just stops seed sprouting. If you really can't spray anything to kill them, then the only option is to pull all those weeds or keep them mowed short and hope the grass chokes them out. Also, some of those weeds will die once the weather gets hot.

I don't know, but i have them too. Mine make little purple flowers. I think it may be a type of spurge. We never had them until this past summer, but we had them in abundance. If they are not cut/mowed, but can grow quite tall. They are easy to pull after a rain, so I made my kids pull quite a few of them, but we still have thousands of them in the grass.

Without knowing what the other grasses are, it makes the decision for us...we cannot use selective herbicides for it. Hopefully you have patches of it and not wide distribution. If so, hit those patches with 2-3 apps of round up (glyphosate). They'll wither away and then you can overseed bare areas. This, again, makes it tough because we don't know what other grasses you need to overseed with. I would recommend spraying before digging in case it is reproducing via stolons...kill it all. Glyphosate will kill whatever grasses it hits. To combat this, I have a set of all different diameter PVC pipe couplings. Actually, I'm preferring the reducers lately, like this: http://www.lowes.com/pd/Charlotte-Pipe-2-in-x-3-in-dia-PVC-Adapter-Coupling-Fitting/3132737 I select the diameter for the size of the grass I want to spray and place it over the top and spray inside the coupling thus saving the grass around it so you only have small bare spots. Now, if you have warm season grasses, those spots might fill right in, but that won't be the case with cool season...you'll need to overseed. Oh, this is important. That stuff, even if we are wrong, has seeded your yard. You'll want to look into pre-emergents like Prodiamine and Dithiopyr. These stay active in the top layer of soil to kill seeds that try to germinate...they do not kill your established grass. Keep in mind, that if you are overseeding, it will kill that too. You have to apply these later...I know Prodiamine is 60 days after seeding. Also, Prodiamine can last 8-9 months in the soil, where Dithiopyr is shorter and can last 3-4 months....depending on rainfall. In short: If you have cool season grass, kill what you need to now. Do your overseed project around the beginning of Sept, and put down Prodiamine around the beginning of Nov. If you have warm season, somebody else will need to comment, but I believe you seed that in the Spring, not fall. I would kill what you need to now and put down Prodiamine 2X between now and again in Nov....re-seed in April...if you even need to. Lastly, if you feel yourself becoming a lawn nut, consider a full renovation so you know exactly what grasses you have and can react accordingly (and with less effort) in the future. Cheers.