What kind of weed

Question: What kind of weed is in the attached picture?  It starts coming in each year around this time and turns brown in late summer or fall.  Is there a way to eradicate it in my lawn?

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied June 20, 2024, 11:47 AM EDT
response: Grassy weed identification can be very challenging from photos, especially once the plants in question have been mown, as this alters their growth habit a bit and removes some identifying features, like flowers or seed heads. The behavior of growing rapidly in summer and dying off by late fall suggest it's a warm-season grass, and two common lawn weeds in that category include Bermudagrass (non-native) and Nimblewill (native). The pictured grass looks a bit too coarse (with larger, rougher-looking leaves) to be either, but it's hard to tell. Management options for both are included in the pages linked above.  Regardless of its identity, the approach may be the same: if it's a summer annual grass, germinating in spring, growing all summer, and going to seed and dying by winter, then removal efforts need to mostly focus on minimizing its seed production and improving the density of the desired lawn grasses so it is less likely to germinate again in spring. Pre-emergent herbicides applied before germination in spring can also suppress its return, though this chemical approach should be the last resort. Overseeding the lawn each autumn with recommended cultivars (if you're able to find one or more of them to use) is one of the best ways to improve lawn vigor and fullness so it out-competes most weed seedlings by itself.  If it's a perennial grass (the same plants survive the winter and regrow every year), it will either need to be physically removed (dug out) or treated with a systemic herbicide to kill the roots (a process that might take a week or two after treatment, or a follow-up treatment at whatever interval the product label directs). There are very few herbicides that would selectively kill lawn weeds that are grasses without harming the desired lawn grasses, and therefore the use of a systemic will probably take out any grass the spray contacts, and the bare patch can then either be seeded or have sod laid to fill it in. The best time of year to sow fescue-type lawns, or lay sod, is in early autumn.  If you want to try to ID the grass, Ohio State has a handy publication that illustrates the physical features of grasses that are used in identification, and a short guide to the differences between some (it's not an exhaustive list) of the common weedy grasses, including Bermudagrass and Nimblewill. (We'll include the version they have for regular lawn grasses in case you happen to key-out one of those by mistake.)  Miri

responder: The Question Asker Replied July 04, 2024, 1:56 PM EDT
response: Thank you for your response.  I have a little more information and pictures to hopefully make it easier to identify.  I'm pretty sure it is not a crab grass.  If I spray it with Spectracide crabgrass killer it does nothing to it, while the regular crabgrass gets killed.  The Spectracide also kills that similar looking  invasive weed/grass that grows in the woods but is larger.  I hope this information along with the attached photos help.  The photos are close ups and a couple show the root system as well. Thanks again for your time and effort. Stephen

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 08, 2024, 8:59 AM EDT
response: Thank you for the additional information and photos, though unfortunately we can't ID the grass in the pictures with the traits visible. You can try using the keys we linked to previously (the two from Ohio State) to try to narrow-down which species it is, though if it's a perennial grass, the options are still probably limited to digging it out or treating it with a systemic herbicide, and replanting once it's dead and removed.  If it is Bermudagrass, it would not be unexpected that no herbicide affects it except for glyphosate. (There appear to be four active ingredient herbicide chemicals in the Spectracide Weed Stop for Lawns Plus Crabgrass Killer, if that is the particular product you are using, but none are glyphosate, and Bermudagrass is not listed among the weeds controlled on its label.)  Miri