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Here is the tool that tells you when to put down Preemerge

Discussion in 'Pesticide & Herbicide Application' started by Armadillolawncare, Feb 4, 2008.

  1. Armadillolawncare

    Armadillolawncare LawnSite Senior Member
    Messages: 570

  2. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

  3. sclawndr

    sclawndr LawnSite Senior Member
    Messages: 326

    That's very amusing but not very helpful. The only thing soil temp tells you though is when it's too late to apply pre-emergent, not when it's time. If you check the label on Dimension for example, it doesn't say anything about soil temperature but instead centers on climate zone, mowing height, etc., which is far more important in determining its effectiveness.
  4. Grandview

    Grandview LawnSite Gold Member
    from WI
    Messages: 3,251

    I go by the calender. I start April 1. That gives me enough time to be done by the first week in May. How much I need to get done determines when I begin.
  5. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    crabgrass germinates at a specific soil temperature, generally it will germinate when the soil temps reach 55 to 60 degrees for 7 to 10 days straight. This often happens at different times each year, depending on what kind of weather you are being dealt. Some years here we don't get the soil warm enough untill the first of may (like last year) but then just the year before the soil temps were holding at 55 to 60 by the first of april!

    The "climate zone map" you see on the bags is simply a map of where those areas usually hit the target temperatures. Lower turf height can slightly effect when the first application is put down, because of it being lower the soil gets more warmth from the sun, but the different application rates are low mowing = higher crabgrass problem and high cut turf = less crab problem.

    It's best to make sure you apply a little early, and I think understands that when you have a long list of customers you have to start and end somewere. That's why doing a split application is the best approach.

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