Zoysia would not remain green in winter, particularly in northern Maryland, so we don't think this is zoysia. It's hard to say exactly what it is, though, since grass ID (outside of clearer traits like winter-dormant) is quite challenging; fine details are needed that we can't see in these photos. Cool-season grasses are likely when they didn't go dormant or have leaves die off in winter. Although a weedy species is possible that won't be in these lists, you can try using the Cool-Season Turfgrass Key by Penn State or Ohio State's Turfgrass Identification Key to see if you can find a match. The guides provide illustrated examples of the structures used to key-out grasses. Virginia Tech has a grassy weed key that does include undesirable lawn grasses, many of which also grow in Maryland, though it will help to narrow-down the results as much as possible if you can find traits like auricles and ligules, when present.

One cool-season lawn weed we've seen more frequently in recent years is Roughstalk Bluegrass (Poa trivialis). As with any perennial weedy grass, it's simplest to physically remove it (dig individual patches, or strip the sod in that area) so you can reseed or sod the area. Herbicides that work best will be systemic and non-selective, meaning they will kill any desirable turf interspersed with the weed anywhere treatments are applied, which will have the same end result as physical removal.

Miri

Does not look like  Roughstalk Bluegrass 

attached are pictures of the same grass on Jan 13

Hello Stan,

We have a correction to make -- one of the turf experts we consulted believes this is indeed zoysia. While zoysia does go dormant in winter, perhaps the entire infiltrated area didn't completely brown if it contained a mixture of zoysia and a cool-season grass (such as fescue). As confirmation, you can see if the traits for zoysia mentioned in the Ohio State key match samples of the suspected zoysia foliage.

Unfortunately, the only way to eradicate it (if desired) is to renovate the lawn. To prevent it from creeping back into the yard in the future, if originating in a neighbor's yard, you might need to use a barrier to block the rhizomes from creeping along the soil surface. If it's instead seeding-in from an unmown yard or natural area, suppress germination in spring with the use of a pre-emergent herbicide labeled for grassy weeds or by relying on dense, vigorous cool-season lawn grasses to out-compete it. Herbicide use will preclude overseeding the lawn in spring, but since the ideal time to overseed cool-season lawn grasses is autumn, there shouldn't be too much conflict. Annual overseeding for cool-season lawns each autumn helps to keep the lawn as dense as possible.

Miri

Hi,

I will check to see if the traits for zoysia in the Ohio State key match what I have.

I will be out of town until next week, but will respond when I check.

thanks

Stan

You're welcome.

I checked the Ohio state key, but could not understand all of thr roots.

Attached are 3 areas of roots I pulled up from the different areas of the grass.

If this is Zoysia, would i need to use Roundup to kill it off and then reseed with tall fescue?

The general growth habit resembles Kentucky Bluegrass, though that species has rhizomes (below-ground creeping stems), with a leaf blade tip will be canoe-shaped (like the prow of a boat), and the blade will have a prominent midrib (the vein running down the center of the leaf). KB can be a common component of fescue seed or sod blends, but it is usually included in fairly small proportions since alone it's not a recommended turf type for our area.

Zoysia turns completely brown in Maryland winters, so the brown blades of the lawn in your prior January photo may indeed be zoysia, with the still-green KB scattered within. We can't make a more concrete identification from the images, but this won't really matter if you wanted to remove this grass and start a new lawn using tall fescue.

Is there a particular reason you wanted to identify the undesirable grass? We ask because, while some herbicide selections do depend on weed type, in this case, it would not -- a non-selective chemical such as glyphosate (Roundup being one example) would be needed for lawn renovation, which will kill any plants to which it is applied. The chemical-free alternative is to physically strip the turf off with a sod cutter machine (or by hand with a spade, which is much more labor-intensive) in order to renovate the area.

Tall fescue seeding is best done in autumn, with the second-best window of time being in spring. If you prefer to renovate now, at this time of year laying sod would be the more practical option since it would more likely be successful, as long as you can keep it watered while it establishes. (The same careful attention to watering is true of seeding, but its watering frequency is much higher since germinating grass seed has little tolerance for drying out.) Sod will probably be more expensive per square foot of coverage than seed, but it's an instant-lawn result with essentially no weed issues (for the first couple of years at least) versus high weed pressure when turf seedlings are germinating and taking time to fill in.
Seeding or Sodding - Lawns

Miri

Hi

I am not clear on this. In the response above  ..this is the reply 

".We have a correction to make -- one of the turf experts we consulted believes this is indeed zoysia...."

It does turn brown in the Winter, but not completely brown. I have a coworker that may want to take some of it

If this is Zoysia...I plan on using something like roundup....the use my tractor to remove the dead grass by scalping it..then using scotts lawn soil to spread over the area .followed by seed...then set a sprinkler to come on early in the am for 10 minutes and in the evening 

I usually start the lawn renovation mid August 

Stan

Hello Stan,

Since the lawn isn't completely brown, we suspect more than one type of turf is present, possibly having seeded-in at some point. As with weedy non-turf grasses (like the Roughstalk Bluegrass mentioned previously), this is a fairly common occurrence. If your coworker is interested in the sod you remove, let them know that is appears to be predominantly zoysia but that other turf types may be present. Since zoysia is the dominant grass, though, the care regimen for zoysia should be used (as cool-season turf care is different).

You can check on the details of lawn renovation techniques and timing in the Lawn Renovation and Overseeding page linked previously. Irrigating only twice a day may not be frequent enough for germinating seed, but it will depend on the weather.

Miri