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switching from a 6 to 7 step program

Discussion in 'Pesticide & Herbicide Application' started by lawnrich, Feb 5, 2007.

  1. lawnrich

    lawnrich LawnSite Member
    Messages: 112

    I will be switching from a 6 to 7 step to fill up my list and to generate more income my question is what are the proplems that could arise from doing a split app of preemergant 4 weeks apart instead of 6 weeks apart. I not worried about less control as much as possible turf damage. Thanks in advance for your advice.
  2. Shades of Green LService

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

    I'd recomend doing your second split in september to get control of fall/winter weeds. Is this a fert combo by the way?
  3. lawnrich

    lawnrich LawnSite Member
    Messages: 112

    yes fert and prem combo so i will use low nitro fert i like the fall idea but its to late for this year can to much preemegent damage turf if its applied in to close a window
  4. Shades of Green LService

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

    I'd reconcider Pe-m (stains) go with dimension.
  5. sildoc

    sildoc LawnSite Silver Member
    Messages: 2,925

    Dimension is a pre-em.
    Pre emergent just as baricade, surflan, casaron, preen and many others. now not all are for turf but they all fall in the pre-em clasification. there are many out there that stain just as some ferts with Iron stain, finding out which do and don't is the key to a quality spread.
  6. Shades of Green LService

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

    Duh PRE-M is a different product(pendamethalin) Dimension ( dithiopyr) Both pre emergents Pendamethalin stains. Dimension doesn't and its an overall better product.
  7. ThreeWide

    ThreeWide LawnSite Bronze Member
    Messages: 1,116

    Not sure how these discussions of different preemergents came about. The original question was regarding damage to turf by applying 2 preemergent applications instead of one.

    Regardless of the preemergent used, splitting the apps is no problem as long as you follow the labeled rates. The product you purchase for each round would be different than before. If you originally used a 0.21%, you might now use two rounds with a 0.10% and also with a reduced amount of N. Since you are going 4 weeks apart, applying a full pound of N per thousand each time would probably not be a good idea.
  8. JWTurfguy

    JWTurfguy LawnSite Senior Member
    Messages: 327

    Good post, Turfunlimited.

    I haven't seen this myself, but studies have shown that going too heavy with preemergents (such as by going at too high a rate, especially with split apps) can encourage Pythium root rot and a host of other problems. Remember, pendi and dimension are basically root-killers. That's how they work (the initial root-sprout from the seed is killed by the herbicide while still in the soil). So going too heavy, especially going too heavy twice, can put unnecessary stress on the roots of the plant. That's a really bad idea, especially if you're second app is timed just before the heat of the summer.

    Follow the label rates for split apps and you'll have success.
  9. ThreeWide

    ThreeWide LawnSite Bronze Member
    Messages: 1,116

    Many moons ago on the web I found a slide set from NC State on the severity of root damage from excessive preemergent applications. They studied most commonly used preemergents and the levels required to produce a clubbed root system along with photos.

    Since they all essentially have the same DNA mode of action, each can cause harm to turf root systems when thresholds are exceeded. Bottom line is that Pendimethalin was more likely to cause clubbed roots, followed by Dimension and Barricade in that particular study. You cannot necessarily conclude from this that one particular preemergent is "better" than another, because both agronomic and economic issues factor into which is the best option for your particular program.
  10. turfsolutions

    turfsolutions LawnSite Senior Member
    Messages: 853

    I'm a believer that you should hold off on preemergants as long as possible in the spring to give the fall seeded grass as long as possible to establish a mature root system. Obviously you have to be careful on new lawns with a history of crabgrass infestation or lawns that have neighbors with crabgrass infestation. Thats not the type of lawn this reply is about.

    They say you should put down preemergant when the forysthia blooms start dropping, or when the soil temps reach around 60 which is usually sometime in April around my way. My problem with this thinking is that I usually don't see any crabgrass emerging on untreated areas until late May. And my split treated areas usually don't have breakthrough problems until July during wet seasons.

    So if you must put down a pre emergant why put it down so early on a healthy lawn with low surrounding crabgrass pressure?

    Wouldn't it be better to wait an extra 2-4 weeks to start your split applications and have more control in July & August when breakthrough is more likely?

    Or, a whole new approach to healthy lawns with low surrounding crabgrass pressure - No pre emergants at all and spot treat with Q4 which will not only knock down the crabgrass, but will be a preemergant for the next 2-3 weeks where applied.

    The benefits -

    more time for fall seeded grass to mature its root system which should translate to deeper roots and more drought tolerancy.

    less pesticides

    The cons-

    Potential for unexpected major crabgrass infestation on certain lawns which would then require a blanket treatment with Q4 or Drive and the usual preemergant.

    I wouldn't try this approach on every lawn. But you guys know your lawns which this can be done with. My own lawn for example has low surrounding crabgrass pressure and has not been treated with a pre emergant in 3 years. Very minimal breakthrough which I have had to spot treat about the same as a lawn with split pre emergant aps applied.

    Don't get me wrong, I would still keep my normal 6 step program but would replace pre emergant applications with products that improve plant and soil health. If you are reluctant to try this on a large scale, experiment with a lawn or 2 and you will be suprised at the results.

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