crabgrass control

Discussion in 'Pesticide & Herbicide Application' started by RigglePLC, Dec 7, 2007.

  1. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,669

    My customers sometimes seem to think it has something to do with Forsythia bloom. They get impatient. Preemergent crabgrass control is critical. Lets plan ahead. How many Growing Degree Days (GDD), base 50, does it take to sprout the first crabgrass in your area? Does your local University have a GDD reccomendation, on the best time, or cut-off GDD when it is too late?

    What is the best date and cutoff date in your area?

    I have seen university recommendations to stop doing crabgrass at anywhere from 70 to 200 GDD. Myself I think up to 500 GDD works fine.

    I am satisfied if I get my crabgrass control done by May 10th. I usually do not see visible tiny crabgrass plants until late May.
  2. mdlwn1

    mdlwn1 LawnSite Silver Member
    Messages: 2,443

    I never had to worry...Barricade can be used when the lawn is basically dormant. Dimension can be used for new signups and late payers untill the CB is around an inch.
  3. Shades of Green LService

    Shades of Green LService LawnSite Bronze Member
    Messages: 1,011

    What about doing split apps rnd 1 & 2 . I think if you do it this way timing is not as crucial, and you'r barrier should last longer than doing one early app.JMO
  4. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Messages: 2,249

    I don't have crabgrass, but some of my attending lawn have it. It shows up along coastal SC about June--I don't look for it till then but sure when the soil temps get to about 70 it sprouts. My applications in Mid-February with Dimension 0-0-7 and then again about May 1 keeps it away. However there are several new things that show up (probably birds) about end of October. Seems that the May 1 app. has pooped out to get these new seeds. Dimension .21 is supposed to be good for 5 months in taller turf, but I question that.
    Shades, this is basically the same as your split application, but the southern coast really start to warm up about the end of March and green up is generaly about mid-April.
  5. MStine315

    MStine315 LawnSite Senior Member
    Messages: 789

    I think forsythia bloom is still a good indicator, but obviously you can't do all your lawns on the DAY forsythia blooms. Mdlw1 echo's my program, barricade early, dimension late. I don't have GDD numbers off the top of my head, but this is a website I use pretty heavy in the spring. I don't know if you've seen it or not, but it's pretty helpful and a good resource. You can forecast 5 days out, too, based on weather forecasts.
  6. rcjc1

    rcjc1 LawnSite Member
    Messages: 1

    I start calculating growing degree days at the first of the year. It takes 110 GDD's to control broadleaf weeds with an ester & 150 Gdd,s to control broadleaves with an amine. Crabgrass will germinate in a thin stand at 200 GDD,s & crab tillering occurs at 850 gdd,s. Hope this helps.

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