Roundup and moss

talkdrums(z7 MD)April 29, 2005

I have read over and over that roundup does not kill moss; however, last fall I sprayed roundup on my back yard to kill the grass in my mostly mossy yard and all the moss where I sprayed turned brown. Looks dead to me. What did I do wrong? Do I have to rake up all the brown stuff and start over? Sigh.

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basil_davis(Z7 N.C.)

I just started growing moss. I spray round up on the moss to kill the weeds. It doese not kill the moss. Round up does make one that will kill moss, but you have to buy the one that killed moss. Did you look at the moss good before you spray? I see a lot of moss at my place growing in grass/weeds that is brown color where I have not sprayed yet. I am going to spray that area as soon as the we have a warmer clear day. I think if you water the moss you see it turn green.

    Bookmark   April 29, 2005 at 11:36PM
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Broken_Pots(z5 IL)

The same thing happened to me some years ago. I think this idea comes from some moss authorities (G. Shenk) who recommend using Roundup to clear an area BEFORE planting moss, it is good because you can plant as soon as it dries. I also suspect that some moss varieties are more vunerable to the spray (especially the 'leafy' kinds) and if they are wet or dry at the time (if dry they will absorb the spray?)
The good news is that the moss will come back faster than the weeds/grass so be patient!

    Bookmark   May 2, 2005 at 3:52AM
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My moss turned brown initially and then came back.

    Bookmark   May 2, 2005 at 7:13AM
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basil_davis(Z7 N.C.)

information from the URL that tenbsmith posted.


One of the most common herbicides in use today is glyphosate (for example in Round-Up). This herbicide is often not effective against mosses (Woodfill 1999; Roberts and Ziegenhagen 1999; Newmaster et al. 1999) but does kill mosses in other cases (Newmaster et al. 1999). This chemical is absorbed through the leaves, becomes tightly bound to the soil, and is degraded by microbes. The failure of many common herbicides against mosses can be seen dramatically in some christmas tree plantations and other perennial crops where competing higher plants have been killed by herbicides, leaving a green carpet of mosses and other bryophytes.

---> The situations in which glyphosate does or does not kill mosses remain unclear I sprayed small area frist. All the moss did great. Then syrayed biger area and all the moss did great. Yesterday I sprayed a big area (use 10 gallons). In this area the moss was already somewhat brown.

Here is a link that might be useful: Chemical Control of Moss in Lawns

    Bookmark   May 2, 2005 at 4:54PM
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I don't remember exactly how long it took for the moss to green up again. I think it had to be a couple of months on average. In the meantime, give it some extra water if you don't get much rain.

    Bookmark   May 3, 2005 at 6:44AM
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We used RU on grass/moss to start a new bed. This was 6wks or more ago. Moss slowly browned and has not greened up again. Its still there and may be alive but looks really bad. So if you WANT your moss, I wouldn't spray RU since even if it doesn't die it looks pretty bad and would be slow to recover.

    Bookmark   May 10, 2005 at 10:53AM
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shadylady_pa(Z6 PA)

I'm testing a new theory of mine - to use vinegar instead of Roundup to kill grass and weeds in mossy areas. I figure that the acidity of the vinegar will not bother the moss, but will be effective against many weeds. In particular, I want to control wild violets. All the other weeds I can remove, the violets are a huge pain to get up and they are all over the place!

I'll let you all know how it turns out.

    Bookmark   May 20, 2005 at 9:13AM
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