The pros and cons of using Roundup for unwanted grass

Laird Stadium at Carleton College Roundup application notice
I’ve been doing a little barefoot running on the luscious green grass at Laird Stadium at Carleton College lately. On Monday, I saw a sign on the gate alerting people that Roundup (Wikipedia entry) had been applied and to “stay off grass until dry.”

Is this a cause for concern? Are there other cost-effective ways to treat a huge area of grass like this? unwanted grass in cracks?

Update 7/16 9 am:  Thanks to the informed comments below, I’ve removed the words “for a healthy lawn” from the blog post title and replaced it with “for unwanted grass.”

I’ve also struck the phrase “a huge area of grass like this” from the second paragraph and replaced it with “unwanted grass in cracks.”


  1. Anne Sawyer said:

    Actually, the Round-up couldn’t have been applied to the entire lawn, unless they were looking to kill everything. Round-up is a non-selective herbicide that kills anything it comes into contact with, including grass. My guess is that they used the round-up to kill weeds/grass that were growing in cracks around the track, and they put up the “keep off the grass” sign to comply with regulations. Also, the residence time of round-up is usually less than 20 minutes… the time it takes to dry. Thus, it’s a very convenient and very effective means of killing weeds.

    That being said, it’s also causing major problems with its overuse… not problems in people, per se, but problems with “superweeds”, or weeds that are developing herbicide resistance. (This is supremely scary, but calls for another thread about GMOs and Monsanto and Round-up ready alfalfa… I won’t go into that now. Here’s one article from the U of MN, though

    There *are* alternatives to killing weeds with Round-up, but they’re not necessarily as efficient nor as successful. For example, you can hand-pull the weeds or smother them with mulch. For pre-emergent uses (i.e. preventing weeds it the grass before they sprout) you can apply corn gluten meal in the spring, but it will take a few years to really see the results. There are schools and other public/private institutions that are using corn gluten meal, but I can’t think of examples off the top of my head – I’ll try to find some links if anyone is interested.

    Oh, and much of this information I’m getting from the U of MN Extension… I’m a Rice County Master Gardener (Intern… it’s my first year). Anyway, here’s a link to all kinds of great into about lawn/garden/herbicide/etc:

    July 15, 2010
  2. Anecdotal evidence from an N of 1: I used corn gluten meal just once on a very dandeliony strip of grass at our old house and noticed a major difference in the first year and thereafter.

    July 15, 2010
  3. Any idea where one can get bulk amounts of corn gluten LOCALLY?

    Buying it by the bag seems very cost prohibitive.

    July 15, 2010
  4. Jane Moline said:

    I have hay fever and contact allergies–and so do my kids. I stay far away from any chemically treated grass–I start wheezing before I even see the posted signs!

    My kids (when younger) would have hives from running across a yard that had been chemically treated.

    However, I have had occasion to use terrible weed killers that are very toxic, like round up, in our pasture for burrdock and thistle. These are very affective but you should wear a haz-mat suit when using. (Yes-very hot this time of year.) I keep the horses out for 24 hours and have had no bad affects when used carefully.

    I think the ground applied fertilizer/weed controll like Scott turf builder are best for lawn care–stay away from liquids and sprays.

    July 15, 2010
  5. Eric Sieger said:

    Griff – I will check with our grounds crew on why we use this product at Laird Stadium. As Anne noted, we use CGM on the rest of our grounds, but often athletic areas are cared for and certainly used differently than the other areas of campus.

    On a side note, with Concordia putting in artificial turf in its football stadium, Laird (Carleton) and Manitou Field (St. Olaf) are the only natural-grass football fields left in the MIAC. So at least you get to run on the real stuff!

    July 15, 2010
  6. There is a farm supply in Farmington just west of and parallel to Hwy 3, down sort of side road where I used to take a friend to buy it by the 40 lb bag fulls.

    I never saw it working very well on her lawn tho. Maybe it was poorly applied.

    We have been hand pulling our broadleaf weeds and it works well if you have the proper weeding tool. Hot water does it, too for small areas.

    July 15, 2010
  7. I’ll just finish up your last line, Jane, by saying that liquids and sprays can travelfurther than you (the general ‘you’) think and end up killing some of the plants you like, either by air or ground, or your good plant roots may be closer than you think to where you are applying the herbicide.

    July 15, 2010
  8. Eric Sieger said:

    @Griff – You can continue your barefoot running program with a clear mind. Just received this note from Dennis Easley, director of grounds at Carleton.

    “The Round-up was used on the cracks in the asphalt between the stadium and the running track. Our note and posting should have been more precise, we’ll correct that in the future.”

    July 16, 2010
  9. Griff Wigley said:

    Thanks much, Eric. I’ve removed the words “for a healthy lawn” from the blog post title and replaced it with “for unwanted grass.”

    I’ve also struck the phrase “a huge area of grass like this” from the second paragraph and replaced it with “unwanted grass in cracks.”

    July 16, 2010

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