Ogemaw weed ID
It is rather hard for me to tell from the picture submitted which weed this one is. It is a grass weed and appears to have rhizomes making it difficult to control using tillage. The tiller would just chop of the rhizomes and redistribute the weed in the garden.
I have to ask if this is a new garden site made from an old pasture. If so this would further explain the weed.
I believe it to be quack grass. At this point in the growing season, you may wish to use a sponge wiper applicator. Roundup or glyphosate may be used but not in the spray form. You would want the foam form in the sponge/wiper applicator. Keep it off of vegetable crops because the Roundup will kill them.
The best options for control are in the fall and the spring. In this case, after the garden is spent for the season, apply Roundup in the spray form to obtain any residual weed control needed going further into the fall and winter. Then after getting a kill, work up the garden and seed it down to the grain crop cereal rye. The cereal rye will help hold the soil in place and gather up any remaining nutrients left that did not get used during the growing season. Then in the spring 1 1/2 to 2 months prior to planting the garden, apply Roundup a second time over the top to kill the Rye cover crop and any quackgrass that may be remaining. You should have better weed control results in 2016 if this plan is followed.
I would be glad to answer any further questions on this topic or any others with vegetable production. Just send me an e-mail or give me a call.