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Roundup and cold Temps

Discussion in 'Pesticide & Herbicide Application' started by ricecake, Feb 15, 2007.

  1. ricecake

    ricecake LawnSite Member
    Posts: 28

    What are some of the coldest temperatures that you guys have seen rounup be effective? I need to spray some beds in the next few days, but the lows here in NC will be 20 and the highs will be around 45. Will I be wasting my time?
  2. DaughtryLC

    DaughtryLC LawnSite Senior Member
    Posts: 739

    works better on a 60 degree day, we will have a few in the next couple of weeks. You know how this NC weather is??!!
  3. Turfdoctor1

    Turfdoctor1 LawnSite Senior Member
    Posts: 705

    if you can wait, wait. however, theoretically, if the plant stays dry, it should take it up and eventually metabolize the chemical resulting in slow death.

    obviously better to wait, but i think that you will get a kill now (maybe not complete kill depending on the weed) as well, just very slow
  4. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Posts: 2,697

    Depends on the contact weed. If the weed is not actively growing, it won't do any good at low temps. Even if it is growing actively, such as a winter annual, R-up is still slow to work. I never use R-up below 55-60 degrees because of it's ineffectiveness.
  5. Runner

    Runner LawnSite Fanatic
    Posts: 13,494

    Yeah,..I've used it in mid t high fifties, and it was slow at best.
  6. txgrassguy

    txgrassguy LawnSite Gold Member
    Posts: 3,083

    A point to remember about glysophate herbicides - they are a salt and kill through severing the apical meristem.
    This function requires an actively growing plant wherein the stomatal pores are open and imbibing nutrients, water, etc necessary for the photosynthesis function.
    At lower temps the pores often either stay closed nor open to any degree thereby decreasing imibition.
    Additionally, in more temperate climates dew points will effect the application of the glyosphate by diluting the herbicide before up-take can occur.
    Should application be absolutely necessary during colder temps, include in the tank a good quality spreader sticker which will effectively decrease the adhesion qualities of the mixture allowing for a more thorough up-take of the herbicide.
    Stay away from soaps as a spreader material as most soaps will decrease the adhesion quality of the herbicide to the point of neutralizing any measurable up-take through the stomatal pores on the target plant.
  7. pesticide

    pesticide LawnSite Member
    Posts: 51

    Glyphosate is a salt that chemically mimics a plant hormome which disrupts the plant's ability to use the necessary enzyme EPSP synthase and thusly after days or weeks the plant dies. Most plants use this enzyme for a plethora of functions and when glyphosate interferes the plant will eventually die.

    google the patent application for roundup by monsanto for a more detailed explanation of the specifics and learn for yourself how it is able to kill. some well-meaning people here really have no clue.

    even on actively growing cold weather weeds glyphosate can take a long time when its this cold. a month or more. for broadleaf weeds tri-power still works and for grassy weeds match the product to the weed. i.e. manor for perinnial rye, corsair for fescues, or if its over FULLY dormant turfgrass use "reward".
  8. dKoester

    dKoester LawnSite Gold Member
    Posts: 3,257

    Here is an easy way to kill the weeds in the cold. Use a propane torch, works great.
  9. ArizPestWeed

    ArizPestWeed LawnSite Bronze Member
    Posts: 1,457

    Is that systemic ?
  10. hmartin

    hmartin LawnSite Senior Member
    Posts: 590

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