Patches of a tall, bluish grass in yard - help please!

Asked June 9, 2020, 11:06 AM EDT

Lawn was planted (drill seeded with hydro mulch) last spring. Seem to come in quite well, but the top soil had a lot of weed seeds in it. Spent most of the first summer/fall hand picking crab grass while the new grass was growing in. Applied Trimec/Drive combo in the late summer/early fall to attack some broad leaf invasion and what appeared to be wild violet that was also invading. Took care of the issues quite well. This spring a new issue has arrived (aside from vole damage that I'm working on). What I thought was some type of Kentucky Bluegrass growing in early this spring appears to be an invasive and unsightly type of annual bluegrass or tall fescue? In the morning, these patches appear almost blueish in color, not lime green like I've seen Poa Annua before. They definitely stand out in color from the rest of the grass and they grow quicker as well. When mowed, it's not as noticeable, but it's been about 5 or 6 day since the last mow and they really stand out. It's about that time to trim it down again, so I've included some pics before the mow.

What is this stuff and how can I get rid of it/manage it? I did not apply a pre-emergent this spring as I opted to core-aerate and over seed to help the extensive vole damage and take care of some spots that didn't grow in as full as I would have liked when the new seed was applied last spring.

Burleigh County North Dakota

5 Responses

Hi Gardener,

Thanks for your question. The photos are helpful.

I shared your information and photos with my colleagues and our weed extension specialist. Two options emerged: goosegrass or orchardgrass.

Goosegrass (Eleusine indica) is a summer annual weed. It is somewhat similar to crabgrass. It will die after a frost. Fortunately, it can be controlled like crabgrass using a pre-emergent chemical such as pendimethalin in spring. This is often included in early spring lawn fertilizer mixes. Since it is an annual, you should be able to easily pull out the plants now. You could try to spray it with a product that contains quinclorac now, but your weed is pretty well established and may tolerate the spray. Weed Be Gon Plus Crabgrass Control is a commonly available herbicide that contains quinclorac. This chemical will not kill your lawn grass.

Another option is orchardgrass (Dactylis glomerata). This is a perennial weed. The only way to control orchardgrass is a targeted spray of glyphosate. Round-up is a common brand name. Glyphosate will kill your lawn grass; use with caution.

Since orchardgrass is a perennial, it may be stronger rooted and may be difficult to pull out.

The easiest way to identify a grass is to see what the seed head looks like. If you could share a photo of that, we would be in great shape. If you have some sample plants (especially with seed heads) and want to send them to or drop them off at my office, I will look at them. I need several plants with their roots as well.

Let me know if you have any follow-up questions. Here are a couple of references:
https://extension.psu.edu/goosegrass-a-summer-annual-grass
https://extension.psu.edu/orchardgrass

Regards,
Tom

Hi Tom,

Thank you for taking the time to look into my question. I sure hope I can come up with a solution that does not include roundup. This grass is EVERYWHERE and would sue make my lawn look petty horrible if I did end up having to spot treat with gyphosate. Since this is my lawn, I do try to maintain a decent lawn length, so finding seed heads was a bit of a challenge, but I did eventually find some. I hope these help out. I tried to find some in various stages of germination.

I also pulled a chunk to expose roots. The last pic I was trying to show the color difference, but is not the same clump that I pulled. These pics don't portray the vast color difference between my normal lawn and the selected grass. This mystery (so far) grass is indeed a blue-ish grey in color.

Thanks for the photos. I'll share them with my weeds expert and get back to you ASAP.

-- Tom

Hi Gardener,

A team of experts have come to a conclusion. Special thanks for your photos of the seedheads -- those were extremely helpful.

You can see two different types of seedheads in your photos. The seedhead on the left, which is light colored, is foxtail barley (Hordeum jubatum).

This is a common problem in our county. I have it myself in the ditch in front of my house. Foxtail barley is a perennial. It will keep coming back, year after year. The bad news is we do not have any herbicides that will kill it, but won't kill your lawn grass. It's a bunch grass, so it can be pulled out fairly easily. Otherwise, you will need to spray it with glyphosate (the standard Round-up is a common trade name for glyphosate, but generic formulations are available in some local garden centers). Glyphosate will also kill your lawn, so you will need to do a targeted spray, making sure you do not spray the lawn grass. Perhaps put an open tube over the weed and spray. Or, perhaps you can kill it with by using a glove and a glyphosate-soaked sponge.

The seedhead on the right is a bromegrass, either Japanese or downy. Bromegrass (Bromus spp.) is an annual grass and will die from frost. You can control it much like you control crabgrass by using a crabgrass preventer such as pendimethalin in your spring lawn fertilizer.

Let me know if you have any follow-up questions. I will be happy to help you. Thanks again for all of your helpful photos.

Regards,
Tom