Pre Emergant Application

Discussion in 'Pesticide & Herbicide Application' started by lwopinc, Sep 8, 2011.

  1. ReddensLawnCare

    ReddensLawnCare LawnSite Bronze Member
    Messages: 1,651

    Crabgrass will not germinate until soil temps reach 50. I usually start my apps when it begins to avg 47 or so. I hit it heavy with dimension first and two months later with pendi. I haven't used stonewall. The only places I have cg come up are edges of drives bc by the time the soil warms up to 50 in the middle of the yard it is typically 10 degrees warmer by the hard surface due to radiant heat so my islNds on my commercials get treated sooner. And you don't need to worry about crabgrass yet, it's a bit to early
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  2. jad004

    jad004 LawnSite Senior Member
    Messages: 282

    I will repeat what Ted has already said. Atrazine may kill it and it may not. If it has some bluegrass mixed in with, then it will kill it. Using atrazine, if it doesn't kill it, will only provide you with 45-60 days of preemerge. Applying prodiamine or any of the other pre's that Ted mentioned will give you at least double the days of protection against crab. I apply my prodiamine in mid march. We use simazine and atrazine as a pre for certain broadleaves and for a post for annual bluegrass in Bermuda grass.
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  3. ted putnam

    ted putnam LawnSite Platinum Member
    Messages: 4,705

    I did not say it would, I said it coulddamage or kill it. Its a "crap shoot."
    If you feel lucky....roll the bones.
    You still won't get any logevity in control of crabgrass using Atrazine or Simazine. Good Luck
  4. ReddensLawnCare

    ReddensLawnCare LawnSite Bronze Member
    Messages: 1,651

    If it's not labeled for it don't use it, especially if it is a RUP
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  5. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 9,975

    Back in the day, before triazine herbicides were under the gun, Ciba Geigy(Syngenta) did extensive testing on what atrazine and simazine could be used on safely. They wanted it to be more than just a corn herbicide. Their research indicated that atrazine and simazine could safely be used on most warm season grasses except for bahia, but never on cool season grasses. There is something about the metabolism of a cool season grass, be it Poa Annua or fescue species that makes it very intolerant of triazine herbicides. Corn could be considered a warm season grass. It needs the heat to grow.

    You are lucky if you are managing fescue in an area that it is adapted. I say that because it will tolerate the common preemergents and broadleaf weed controls. On my lawns, which are usually bermuda or zoysia cut at golf course heights, Pre-M or Barricade are damaging and I have to watch Three Way type products. If you are trying to prevent crabgrass in tall fescue, nothing wrong with a split application of Pre-M, you can throw in Gallery DF in the first application of the split of broadleaf weeds are a problem.

    I consider triazine herbicides to be more of a postemergent product. Yes, they do kill weeds germinating on seeds. However, when applied to an irrigated lawn, enough of it moves down to kill any vegetation not tolerant. I have heard of people killing trees and shrubs if the soil was alkaline or sandy.
  6. cecropia11

    cecropia11 LawnSite Member
    Messages: 103

    what about DITHIOPYR 40 WSB HERBICIDE split applications to the highest use rates. has anyone had any experience with it, does it work better than prodiamine 65 WDG, on grassy weeds

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