Lawn Problems
Q.

Is this Poa annua?

Zone bristol, ct | rachinc added on January 12, 2017 | Answered

Is this Poa annua? If so, what's the best remedy to kill it? I have these patches of grass in my front and backyard. When I drive over them with my rotary lawnmower, it feels like I've hit a rock. It makes it very difficult to mow the lawn. It's everywhere. I asked my lawn company, TruGreen, if they have a herbicide to kill it. They said no but they have roundup. Not the response I was hoping to hear. I asked if I could pay them to buy and apply the herbicide to this stuff in my lawn. Their answer wasn't yes or no, they just ignorantly repeated that they don't have that herbicide. If you want something done, do it yourself right? Well, I'm ready to buy the herbicide and do it myself but I'm not totally convinced that this is Poa Annua/Kentucky bluegrass. So before I pull the trigger and buy something that might not work, I wanted to get other people's opinions. Based on the provided images below, let me know what you think. In the spring the top of the grass (in certain patches/places) looked like this http://hasbrouck.asu.edu/imglib/seinet/Poaceae/photos/Poa-annua-FL-web-N3658.jpg

A.
A.Answers to this queston: Add Answer
Alisma
Certified GKH Gardening Expert
Answered on January 13, 2017

The first image does look like Poa annua, and the grass in the video appears to be Poa annua too. It is commonly known as bluegrass, but the stems can be purplish too as seen in the video.

Poa annua found in lawns is most commonly an annual grass, while most lawn grasses are perennial, so two measures you can take to reduce this weed's population in your lawn are 1. mowing often enough so that the Poa annua doesn't have a chance to produce seeds, and 2. using a pre-emergence herbicide to prevent the Poa annua seeds from sprouting, as described in this article:
https://www.gardeningknowhow.com/plant-problems/weeds/poa-annua-control.htm

Here is more information about preemergence herbicides which can be applied in the late summer and early fall as well as other control methods:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7464.html

Once you've reduced the Poa annua population to a small size, you can remove the last few plants by hand.

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rachinc
Answered on January 13, 2017

I'm way beyond a per-emmergent at this point. i'm at the point where I'm mowing the lawn and it feels like I've hit a rock whenever I run into this stuff/mow over it with the rotary mower. I'm guessing pre-emmergents wont decrease the hardness/make these "rocks" go away?? So I'm going to need a different solution. If i use roundup on them, will it still feel like i've hit a rock? or will they soften up (as well as die) with roundup? Or will a certain herbicide make them disappear all together without sitting there looking dead and brown in the ground (From the roundup)?

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