Is glyphosate effective in cooler temps

Discussion in 'Pesticide & Herbicide Application' started by Armadillolawncare, Dec 9, 2007.

  1. Armadillolawncare

    Armadillolawncare LawnSite Senior Member
    Messages: 570

    How cool can it be to get effective results when using glyphosate? Can I use it effectively when the temps are in the 40s? I have an area of my yard that I want to sod but I would prefer to kill the weeds as opposed to just cutting them back or hand pulling.
  2. Marcos

    Marcos LawnSite Gold Member
    Messages: 3,720

    Yes, it still works. But it works a lot s-l-o-w-e-r when it's cooler out.
    Go ahead and follow the label directions for the 'higher' end of the recommended rate. Wait about a week and then sod.

    I don't recommend using anything with diquat like Roundup Quikpro prior to laying sod. Diquat leaves a residual that may harm the rooting of the sod.
  3. Grandview

    Grandview LawnSite Gold Member
    from WI
    Messages: 3,251

    If what you are trying to kill is still green, glyphosate should kill it. It is more effective on grasses than broad leaf weeds in my opinion.
  4. Armadillolawncare

    Armadillolawncare LawnSite Senior Member
    Messages: 570

    OK great, thanks for the help.
  5. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    What they are trying to tell you, is Plants must be actively growing in order to up take the Herbicide. If the weather is cool or cold then the ground temperature is also low. It is Ground temperature that plays the big factor in how actively growing a plant is. Different plants will slow or stop growing and go dormant at different ground temperatures. So there is no cut and dry answer to your question.
  6. maintenanceguy

    maintenanceguy LawnSite Member
    from NJ
    Messages: 156

    glyphosate works by blocking a plant's ability to use sunlight to produce sugar. When plants are actively growing, they need lots of sugar and die fast without it. When they're dormant, they need almost no sugar. At 40degrees, you won't see anything die off until the weather warms up. But I don't know if an application now will last that long.
  7. Bryn

    Bryn LawnSite Member
    Messages: 209

    Hi Ric,

    Have not been on the borad in a long time, so while sitting in an internet coffee house, I thougt I would look through the board and came across a post by you. Had not seen a post from you in a while, and missed your common sense replies.

    Pest control has been keeping me very busy, so HLT has been put on hold while I get my pest techs up and running. Maybe in a year or two I will get a chance to build my HLT business more. Life is good, especially when you wake up above room temp, so I don't complain.

    I will look for more of your posts.

    Best Regards


    Elite Pest & Lawn Solutions, LLC
  8. rcreech

    rcreech Sponsor
    Male, from OHIO
    Messages: 6,153

    What you say is mostly true...but what you need to keep in mind is also what type of weeds you are trying to kill!

    We fall/winter spray our fields up here for winter annuals (ie chickweed, henbit etc) and I spray as long as the air temp is about 32 deg. And that is just to keep from freezing at the tip!

    Point is, it depends on what type of weed you are trying to kill and its growth habits.
  9. Armadillolawncare

    Armadillolawncare LawnSite Senior Member
    Messages: 570

    Well I guess I can just try it and see what kind of results I get.
  10. rcreech

    rcreech Sponsor
    Male, from OHIO
    Messages: 6,153

    That is probably the best idea! Just try it and see if it works for you.

    I can spray now and the weeds will stay green most of the winter. But as soon as the snow melts or spring time comes...fields are as clean as can be!

    It just takes a lot more time to get a kill when temps are lower!

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