hot weather and herbicide

Discussion in 'Pesticide & Herbicide Application' started by RigglePLC, Aug 28, 2014.

  1. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,808

    I tested four herbicides in hot weather for potential damage to grass.
    However DARN! Cool year--our first predicted 90 degree day of the year did not happen, as it rained. Temperatures remained about 85 and then fell to about 80 in the next two days. I used: a 3-way, Surge, Speedzone, and T-Zone, each with surfactant, except the 3-way which was a ready to use spray bottle. I used approximately label rate and applied to7 inch diameter circles, one time, three times over and 5 times over. I calculated it at about a half-gallon per thousand sqft as the water rate.
    I applied to bluegrass/ryegrass mixture in light shade, and in a second area, Bermuda in a full-sun area.
    After 72 hours--no injury to either species of grass was visible. Stay tuned.
  2. americanlawn

    americanlawn LawnSite Fanatic
    from midwest
    Messages: 5,956

    Cool deal right there Riggle. Im did a little research myself regarding amine herbicides... seems amines are more often likely to cause turf damage compared to esters. I have experienced this for nearly 35 years, so I can personally verify this. The ONLY good thing I can say about (cheap) 3-way amines is they're cheap. $24 per galon compared to $58 (or more) per gallon of the good stuff. my 2 cents, and I thank you for all your good info. :waving:

    CHARLES CUE LawnSite Silver Member
    Messages: 2,462

    Hell 90 is to hot to be out there let alone spray weeds. May be the reason esters don't burn is they evaporated before they had a chance to burn at 90
  4. Dr. Cornwallis

    Dr. Cornwallis LawnSite Senior Member
    Messages: 854

    I would kill for just a 90 degree day here in fl.
    Posted via Mobile Device

    CHARLES CUE LawnSite Silver Member
    Messages: 2,462

    I knew some would say this there no way I would live in Florida 32deg is great. Its going to be close to 90 tomorrow cant wait for OCT
  6. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,808

    After 5 days most treatments showed injury at the 5 times rate. Temperatures were about 80 as highs and a few rain showers occurred.
    On the bluegrass/rye injury to grass was:
    Speedzone medium
    T-Zone medium
    Surge none
    a 3-way medium

    On the Bermuda grass mixture injury to grass was:
    T-Zone severe
    Surge severe
    Speedzone severe
    a 3-way slight
  7. Skipster

    Skipster LawnSite Bronze Member
    Messages: 1,086

    A couple of questions:

    1) What do you mean by applying the "label rate" of your chosen products? The labels for all of the products you listed give ranges of rates for application. None of them specify one single rate to use. So, which rate did you select for each one and why? Very often, the maximum single application rate on the label is more than what's needed for excellent weed control. Just because it's the highest allowed on the label doesn't mean that particular rate kills the weed any deader.

    2) What's the purpose of the 3x and 5 x rates? What should we take away from your selection and the results with those rates?
  8. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,808

    Good point, Skip. I usually use the maximum rate. I want to kill all the weeds--easier than returning to respray.

    The 3X and 5X rates were intended to indicate whether or not there is a margin for error, particularly at high temperatures. (Which didn't really occur.) Spot spraying is necessarily imprecise--more so if the applicator is unskilled or careless. Clearly, careful calibration is mandatory. A sweeping motion is important when spot spraying--as opposed to holding the nozzle close for a point and shoot action.

    I will check the sprayed spots again in the next few days--to see if more damage becomes evident.
  9. americanlawn

    americanlawn LawnSite Fanatic
    from midwest
    Messages: 5,956

    Regarding a sweeping motion (back & forth), I prefer a constant/forward motion with the wand.

    I also like Skip's question >> We use 1.10 - 1.50 ounce per one thousand sq ft regarding "hose spraying" and "stand-on spreader/sprayers". We also add 1 - 1 1/2 quarts per 100 galon fill of LI-700.

    But during hot & humid weather, we actually "violate" label recommendations (in our state). Cuz we will go as low at 0.80 ounces per 1000 sq ft. This is because stomates open up wide and take in herbicides very easilly & quickly. Some states allow for below label recommebdations, but my state does not.

    I wish I never left Texas, cuz Iowa sucks the big one. :hammerhead:
  10. Skipster

    Skipster LawnSite Bronze Member
    Messages: 1,086

    I’m not sure that the maximum rate will always kill “all the weeds” better than a lower rate. If you only look at 2,4-D (common to all products you used here), Trimec Classic (the 3-way label I have handy right now) applies 0.99# ae/A, Surge applies 0.7# ae/A, SpeedZone applies 0.94# ae/A, and T-Zone applies 0.875# ae/A. There are other actives in those products , too, but if the objective were to use the most stuff because it kills the most stuff the deadest, why would anyone use anything other than a 3-way? This is why research is done to determine what rates are needed. The highest isn’t always the best.

    Just like americanlawn, I’m wondering about this “sweeping motion.” Can you explain what you mean by "A sweeping motion is important when spot spraying" and why you think spot spraying is necessarily imprecise?

    Maybe to get the best understanding of what you’re trying to accomplish, we need to lay a foundation. What do you consider to be “spot spraying” and how do you accomplish it?

Share This Page