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Is 1/2 gallon per 1000 sq ft enough for pre?

Discussion in 'Pesticide & Herbicide Application' started by grassmasterswilson, Feb 20, 2009.

  1. grassmasterswilson

    grassmasterswilson LawnSite Platinum Member
    from nc
    Posts: 4,548

    I got my spray calibrated at .55 gallons per 1000 sq ft right now for my pre emergent and winter weed kill. Do you guys think that is enough carrier? I have some people say water is your enemy and use the least amount. Then I hear people say with pre emergent you want good volume and go with 1 gal per 1000.

    comments? ideas?
  2. Ric

    Ric LawnSite Fanatic
    Posts: 11,956


    I don't feel 0.55 gallons per thousand are enough to get good coverage of any product. But there are different schools of thought on this subject. In your case I would make sure to irrigate immediately.
  3. Turfdoctor1

    Turfdoctor1 LawnSite Senior Member
    Posts: 705

    You never hear about a golf course spraying at GPA that are above this, and they get the job done.

    I realize it is a different animal, but I still believe that you can have good coverage at those volumes.
  4. FdLLawnMan

    FdLLawnMan LawnSite Bronze Member
    Posts: 1,182

    Think about it, if you spread a granular pre-emergent you are using no water at all. As long as it gets watered in in a day or two you will have no problem. The problem with using WSP pre-emergents is that they it experience photo-degradation in several days. That is why watering in is so important.
  5. Think Green

    Think Green LawnSite Silver Member
    Posts: 2,746

    Golf courses water--water--water daily! I feel that they can spray their products at .55 gallons per thousand. They are worried about the drift factor. They are
    applying mixture with shielded machinery at a height of 8 inches from the turf.
    If you are spraying in a residential setting, with a shielded applicator, then rest assured, the customer must have a watering system or get water to the product quickly. I would hope that all your customers are watering!
    Granular products are similar, yes they need watering too, but will become inactive without water through ultraviolet degredation. Dry soils need the extra water volume to help the powdered mixtures get down. The 1/2 inch of extra rain or whatever will only help the process naturally.

    Are you using a boom type applicator? If not, what about the drift factor in using a preemerge for residential or commercial? Maybe, you are doing golf course or industrials, I don't know, but I was taught on the residential side of applications, that as long as you have enough water to adequately cover the surface of the soil in solution, weed supression or control is optimum at recommended label rates. My system delivers 2 gallons of water per 1,000 sq.ft. with a lawn shower gun for preemerges only. I change nozzles for postemerges so I won't have drift as much. As large droplet of water will cover more ground as per say, a finer mist would.. Common Sense!, so it all depends on your application method. The othe professionals in my area are using shower guns--Z sprays--back packs--that is all. The larger properties are done with the shielded Z sprayers customized to each applicator.
  6. greendoctor

    greendoctor LawnSite Fanatic
    Posts: 9,064

    I worry about drift too. That and coverage. Chemicals do not kill or prevent emergence if they do not hit where the weed or seed is. If the droplets are too far apart, do not even land on the target or are so big that roll off occurs(postemergent), I do not expect good control. I spray through a boom or single nozzle wand with air induction tips and a minimum of 1 gallon/M. The other thing to consider is if a herbicide is volatile, the less water carrier, the more easily it evaporates into the air. I do not think it would be safe or effective for me to apply something like 2,4-D ester in 85 degree heat, high humidity and 5-10 MPH winds if I tried to do it in less than 1 gallon of water. I have different weeds here. They are often annuals that have been growing for over a year, making them woody and hardened off. Most of them have very small leaves with a prostrate growth habit. A floodjet tip applying 5-10 gallons per acre does not do it. Neither does a Chemlawn gun.

    To answer the original question, 20 gallons per acre/1/2 gallon/M is fine for preemergents if it is being sprayed through a boom fitted with flat fan nozzles and irrigation will follow the application as soon as possible.
  7. Grandview

    Grandview LawnSite Gold Member
    from WI
    Posts: 3,251

    I spray 5 gal/acre for post emergence. Have done this for 15 years and getting excellent results. I use air induction nozzles and Interlock to reduce drifting. I have never done pre emergent spraying always granular. I would feel comfortable with coverage at 5gal/acre. I would worry about the degradation if not watered in. It probably depends on what you use. On the ag side they spray some prems on bare ground. It could sit on top for a week to 10 days without rain.
  8. Ric

    Ric LawnSite Fanatic
    Posts: 11,956


    I am sorry I put my 2 cent in here because I knew when I posted the ride on guys would jump me. But I did try to hedge my reply by saying there are different schools of thought.

    IMHO chemicals need to be watered in, Homeowners are not readily available to turn on irrigation every time. Therefore I, and many in my area apply at 5 gallons per thousand so we water in our chemicals that the homeowner doesn't. Once again I know others do it at 1/10 my rate with success. Good for you
  9. Runner

    Runner LawnSite Fanatic
    Posts: 13,494

    There is no way I would trust even myself at 1/2 gal./1000 through a skid. That is HOT. With a LV machine like a Permagreen (which sprays at even half of THIS), it is better calibrated - as it is a smooth movement of ground speed, combined with a solid width. With a skid, there is more of an overlapping pattern both in the side to side and even some row by row. When I sprayed from a skid, I was spraying 1 gal./1000, and THAT was hot! I sure don't recommend this to ANYone who isn't well seasoned with a tank and gun.
  10. greendoctor

    greendoctor LawnSite Fanatic
    Posts: 9,064

    I can do 1/2 gallon/M through a walking boom. But that is a hot mix and I have concerns about coverage. Weeds are not controlled where the spray does not cover. If you are talking about swinging a gun, drops land far apart at that volume.

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