herbicide injury potential to grass

Discussion in 'Fertilizer Application' started by RigglePLC, Jun 27, 2014.

  1. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,670

    Five different herbicides and 2 combinations were tested for the chance of injury to Kentucky blue/rye/fine fescue. Surfactant was included at about one-half percent. T-zone, Speedzone, Quicksilver, a 3-way, and Surge were tested and also the combinations Speedzone plus Quicksilver-- and T-Zone plus a three way.

    Using squirt bottles which applied about 1/30 on an ounce per squirt, I applied six squirts, about 6 times over the usual rate.

    The soil was moist due to rain before and after. Temperature highs were about 84.
    Only Speedzone and Speedzone plus Quicksilver resulted in injury to the grass.
    Left to right:
    T-Zone, Speedzone, Quicksilver. Second picture: a 3-way, Surge, Speedzone plus Quicksilver, T-zone plus a 3-way.

    Just thought you would want to know.


  2. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,670

    Twelve days after treatment with 6 times the proper dosage--only Quicksilver and a generic three way showed no sign of phytotoxicity injury to the turfgrass. Speedzone showed the most damage, along with medium damage from Speedzone plus Quicksilver. T-Zone and Surge separately both showed slight damage.

    It appears that the chance of injury from a generic three way is relatively low.
  3. Skipster

    Skipster LawnSite Bronze Member
    Messages: 1,076

    1) What area did you cover with the bottle spray? Was it consistently covered, or did it spray in a cone shape? How did the droplet size compare to conventional sprayer nozzles?

    2) Why did you include a surfactant with these herbicides? These labels don't recommend using surfactants. They even say that using surfactants can cause turf injury.

    3) Why would you mix SpeedZone + Quicksilver?

    4) Why would you mix T-Zone + "3-way" (whatever that is)? What rates did you use? If you're using single application maximums for each, you're exceeding the maximum amount of 2,4-D allowed in a single application.

    5) How do the ai rates in your treatments compare? Are you comparing the same ai rates across products, or do some product apply more of some a.i.s than others?

    Just wondering how this information could be used.
  4. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,670

    the area covered was about 1/2 sqft (a circle 9.6 inches diameter). The droplets were fine, no cone shape, but due to the spray angle the pattern was more egg-shaped- maybe even parabolic.
    I included a surfactant, because when I was in business, that was my standard practice--and--I wanted to know if the surfactant would cause injury.
    I mixed products partly because sponsored university research seldom mixes the products of two different companies. I also wanted to find if any combinations are highly phytotoxic to turfgrass.
    The three way is Ace Hardware's version of Trimec in their "Ready to Use" squirt bottle.
    My measurements were naturally, approximate. I tried to use label rate with one squirt. Of course 6 times over is far in excess of the normal rate.
    I wanted to allow for sloppy calibration and hot dry weather--which can happen.
  5. White Gardens

    White Gardens LawnSite Fanatic
    Messages: 6,776

    Speedzone is an ester for cool season applications. Not the least bit surprised it caused injury.

    Was the quicksilver an ester?

  6. Skipster

    Skipster LawnSite Bronze Member
    Messages: 1,076

    The reason that I asked the questions that I did is to try to determine if the results are applicable to real world conditions or scenarios. The relationship of the droplet sizes is important because it relates to coverage. If you used a smaller droplet size and more squirts, you could have covered the turf with more material than what would be reasonably expected from a standard application (backpack or such). Thus, the results would be skewed and not reflective of real world conditions.

    Maybe adding surfactant was your standard practice (even though the manufacturers expressly stated that it can cause injury), but you didn’t test what you’re claiming – whether adding surfactant caused injury. To do that, you would have to use a factorial treatment design: test the herbicide with and without surfactant. Since you said you put surfactant in all of them and didn’t include a non-surfactant treatment, we have no way of knowing if the herbicide would have caused the damage without the surfactant or not. Maybe the damage would have happened without the surfactant, but you didn’t test that.

    Also, what product rates did you use? Most herbicide labels provide ranges for use rates. A lot of guys think that only the highest rate on the label should be used, but that isn’t always necessary. Using more herbicide than necessary isn’t going to kill a weed and deader than using the right amount.

    Not knowing the exact product rates you used makes it hard to compare ai rates, but did you compare similar ai amounts? If you use the single application label max, Surge applies 30% less 2,4-D than 3-way.

    Why don’t universities test all of these combinations? Because they test active ingredients, not random products. 2,4-D is effective on a broad range of lawn weeds at 0.9# ae/A. University professors understand that combining T-Zone + 3-way, as you did, just gives you (triclopyr + sulfentrazone + 2,4-D + dicamba) + (2,4-D + MCPP + dicamba), a total of about 1.88# ae 2,4-D/A and no better weed control than just one of the products by itself.

    Are you saying that Speedzone + Quicksilver or T-Zone + 3-way are common or desirable mixtures for LCO?
  7. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,670

    Quicksilver is not an ester.
    Good questions, Skip.
    I only had one nozzle available; adjustable, filled cone. Droplet size is variable, naturally. Except for the Ace hardware pre-mix ready-to-use three way, I didn't test without surfactant, (did that last year).
    I can test surfactant phytotoxicity at zero, low and high rates in the next few days, (with water). I want to do that when the weather is warmer. Some members here have expressed reluctance to use surfactants in hot weather--I would like to know if there is any basis for that idea.

    I try to use the high label rate. I am interested in the combination of products, and surfactants. In any case, I don't have new active ingredients to test.
    I would like to find a combination that is more effective on the tougher weeds, like: veronica, spurge, violets, ground ivy and oxalis.
    I think some of the claims of the surfactant and wetting agent manufacturers are a bit exaggerated--but maybe you know better than me. You have done a lot of such tests. If control can be improved using a surfactant--by what percent, 110 percent? 130 percent? Does it depend on the weed? Not needed with some products?
  8. americanlawn

    americanlawn LawnSite Fanatic
    from midwest
    Messages: 5,954

    We see slight turf burn on new accounts that are chalk full of weeds (during warm weather). This is because we spray a heavier volume in order to clean up those lawns a.s.a.p. (but the turf usually recovers after a couple of mowings). I'm talkin 1.5 oz per K compared to 1.0 oz per K. BTW... going less than 1.1 oz per K is "off label" for many bwc (broadleaf weed controls). In some states, it's illegal to apply LESS than 1.1 oz per K (label) >>>>weird.

    During warm or humid weather, we reduce the herbicide rates. Cool temps or low humidity = we increase the rates

    I like LI-700 the best. It buffers the high pH of our alkaline water. It's also a spreader/sticker. It also acts as a penetrent to allow the herbicide to enter the weed tissue more easily.

    We blend our broadleaf herbicides according to weather conditions or target pest. I won't comment any more for now, but "amine 3-ways" are cheap, and they only can kill easy-to-kill weeds. imo

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