Pre-Em apps & heavy downpours

Discussion in 'Pesticide & Herbicide Application' started by khutch, Sep 14, 2004.

  1. khutch

    khutch LawnSite Senior Member
    Messages: 495

    Well it's nice when Mother Nature waters in our Pre-Em apps, but I am wondering, when does it cause a problem? On slopes the heavy downpours have got to wash away quite a bit.....Pre-Em is almost like powder, once it "melts", is it in the soil and good to go? What happens when you get 6 inchs of rain on top of a new app? My debate is if I should wait until Ivan the Terrible gets by us to get these apps out of the way....

    GREENITUP LawnSite Senior Member
    Messages: 274

    khutch, what kind of pre-em. are you putting down this time of year? most people in our area are seeding in sept. and oct. and you might want to read the lable very carefully if you have any new seed down.
    as for the direct question - some of a grannular app. will float away from a very heavy downpour right afterwards. we usually wait a week or two and see if it starts to take effect before any re-app. is done.
    good luck.
  3. khutch

    khutch LawnSite Senior Member
    Messages: 495

    Using Lesco Pre-Em (0-0-7) for my warm season (Zoysia, Bermuda) accounts....
    Only problem with waiting is you get farther and farther behind (I like a Sept. 15 deadline for Pre-Em) and w/Pre-em you don't get to see if it "is working"!
    Well, until next year I guess........
  4. ThreeWide

    ThreeWide LawnSite Bronze Member
    Messages: 1,116

    I was facing the same dilemma as you last week. I chose to wait until Frances passed fearing that 6 plus inches of rain would wash away my pre-em.

    A local contact of mine who has been doing this for years assured me that the pre-em would not wash away before becoming soluable. I could not stand to wait any longer with Ivan coming, so my accounts were all applied yesterday and today.

    I would be nervous to hold off another week. We've had morning temps near 60 at my home the last day or two, so the poa annua will start up very soon.
  5. greenerpastures

    greenerpastures LawnSite Member
    Messages: 160

    Have you considered holding off for a while and using simazine on your warm-season turf? Longer residual and it has decent post-emerge action on poa, but not really suited for granular application.

    Any type of washing rain, definitely those associated with hurricanes, weaken a treatment either through runoff or leaching. Runoff losses are more likely soon after apps---I hope your spared this storm.

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