Winter preemergent

Discussion in 'Pesticide & Herbicide Application' started by LawnsharkMB, Sep 30, 2012.

  1. LawnsharkMB

    LawnsharkMB LawnSite Senior Member
    Messages: 650

    How do you decide when to put down pre em for poa? Do you go by a certain date or is there a specific temperature to look for like you do with crabgrass?
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  2. Trueturf

    Trueturf LawnSite Member
    Messages: 22

    There has been a good bit of research that suggests a lot of poa actually germinates late August early September. Which is typically earlier than we go out with our pre-emerges. I have found that two split apps of barricade one in August and one late September really decreases poa populations. If you want to go even better add Monument or Certainty to the September app.
    Hope this helps.
  3. LawnsharkMB

    LawnsharkMB LawnSite Senior Member
    Messages: 650

    Where are you located? I'm in Myrtle Beach where the temps are getting down in the 50's at night and the highs are in the 70's. we still haven't put out pre emergent because a guy at JDL told the owner to wait a couple more weeks even though most companies and golf courses have already put it out or are doing so now.
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  4. JBNC

    JBNC LawnSite Member
    Messages: 200

    We've been putting it down for a week here in NC.
  5. ted putnam

    ted putnam LawnSite Platinum Member
    Messages: 4,731

    I'm in Central Arkansas and am seeing newly emerged Poa in shady , thin areas. I am also seeing quite a bit of Bittercress, Henbit and Red Deadnettle emerging as well(mostly in newer customers. We have been spraying for 3+ weeks now and wouldn't do it any other way.

    My philosophy on the concept of Pre-emergent is that "Pre" is the key part of the term. By starting a little early, we're more likely to beat the weeds and the leaves. I've been starting earlier for the last 4 or 5 yrs and it works well for us. To each their own.

    IMO, if you're in about the same latitude as me and you just started or are about to start applying your Pre-emerg, you are behind the eight ball.
  6. Skipster

    Skipster LawnSite Bronze Member
    Messages: 1,086

    ^^^^^^ This is your biggest problem ^^^^^^^^

    To answer your original questions, I usually look for a calendar date when making the fall applications. Annual bluegrass germinates most rapidly when soil temps at the 2" depth are between 68 and 72 F (Clemson and NCSU research), with germination dropping to near zero when soil temps at 2" depth are below 58 and above 78. Because this can vary between properties and location within a property (shady areas, etc), I look for the calendar date that will be close to these temps, then back up my start date to allow me to treat my customer before this prime germination period.

    But, you're main problem is proably basing your decisions off the JDL guy. His job is to sell product, not provide service to your customers -- that's your job. I've met a lot of really nice guys at dsitributor locations over the years, but I wouldn't put my business decisions in their hands.

    Since you're in Myrtle Beach, annual bluegrass will probably germinate later in your area than it will for those of us farther north or farther inland. My biggest caveat would be to match your application rates to soil type. Snady soils generally need a higher rate or more frequent application than heavier soils.

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