herbicide spray on new grass

Discussion in 'Pesticide & Herbicide Application' started by RigglePLC, Jul 26, 2011.

  1. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,659

    I did a small weed spray experiment (preliminary) on newly seeded grass. I planted the grass in containers on July 16 2011. It sprouted 4 days later. I sprayed it with herbicides 7 days later on July 23. It was about 1.5 inches tall. Temperatures were in high eighties in daytime and 70's at night. The treatments were: T-Zone double sprayed, T-Zone 4 times sprayed, Lesco Eliminate double sprayed, and Lesco Eliminate 4 times sprayed.

    Results: The sprouts sprayed with T-Zone were injured, especially at the 4 times rate, as they collapsed. The area from about 1/4 inch above the soil to one-inch was brown, necrotic and collapsed. Most of the sprouts bent over at this point.

    There was no visible injury to the seedling sprayed with Lesco Eliminate--either at the 2 times or 4 times sprayed test. The product worked well on other nearby weeds which were sprayed.
    I suspect the difference may be due to the sulfentrazone in the T-Zone formula.

    Seed sown was Scotts "High Traffic" which is high in Silverdollar perennial ryegrass.

    It appears from this test that Lesco Eliminate is relatively safe for new grass.

    Last edited: Jul 26, 2011
  2. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 9,974

    I have known that low rates of amine or ester based broadleaf weed control are safe on newly planted lawns. No need to get crazy with the rates because the weeds are new and not hardened off either.
  3. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    Grassy Weed Herbicide like MSMA and Tenacity are also safe to apply on newly germinated Grass seed.

    BTW While Bermuda is not listed on the Tenacity Label, I have used it on my own Common Bermuda with no signs of any stress in the current summer heat.
  4. yardsmart

    yardsmart LawnSite Member
    Messages: 58

    View attachment tenacity on bermuda.pdf Look under (Use Precautions and Restricition) Im glad to here tenacity works on bermudagrass. I was curious on how you applied it(spot or broad)? At what rate? Target pest? Time line of total kill? Repeat spray? Weather conditions(how hot)? I wanted to spray(spot spray) crabgrass and other grassy weed with this product or as a mix. The label says bermudagrass is sensitive to this product. This would be very good info if you figured out a good mix rate without any damage to the bermudagrass.
  5. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    I just walked my yard that was sprayed with Tenacity about 10 days ago. What I can tell you is spot spraying it heavy, does turn Bermuda white. So I am not sure I didn't damage it in spots. In general where I sprayed Crab Grass at a calibrated rate the Crab Grass turned white and the Bermuda didn't. But then if you spray St Augustine heavy it turns white but recovers.

    Seeding Bermuda is a real weed problem here in South Florida. We have a limited window and that window is rainy season which really drives the Crab Grass and Sedge. MSMA does a great job on both and not new seedling. But I am looking for something that works and is still on the market.
  6. grassman177

    grassman177 LawnSite Fanatic
    Messages: 9,795

    i had no idea with how hot chemically msma is that it did not torch seedlings. interesting.
  7. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 9,974

    Apparenly, Tenacity by itself at moderate rates is not enough to knock down healthy bermuda. The best mix for that involves Acclaim Extra, Tenacity and Turflon Ester. http://turf.lib.msu.edu/ressum/2008/64.pdf I am hoping that it is found that bermuda will tolerate carefully applied Tenacity because it is one of the few selective controls for grasses of the species Chloris(windmill grass) and Eragrostis(lovegrass). Unless a rate and application protocol safe to use in bermuda in the tropics is found, Syngenta will not bother registering Tenacity in Hawaii.

    In the past, I have used MSMA on newly seeded bermuda without issues. It stands to reason based on how minimally injurious it is to my typical lawn that is not treated unless it is well watered and well fertilized. A newly seeded lawn is both of those. I expect MSMA to burn up a lawn that is minimally fertilized and only gets water if it rains.
  8. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    The mix in bold above is for selective control of Bermuda in Kentucky Blue Grass. while this might be of value to our Northern Members, it does nothing for St augustine other than kill it dead also. But then my Bermuda Mix for St Augustine might just kill Kentucky Blue Grass dead
  9. Yaunt2

    Yaunt2 LawnSite Member
    from OK
    Messages: 13

    I had great results seeding my Riviera Bermuda yard using Drive XLR8 before & after seeding. I had full coverage by late June, and it survived the worst winter storm with zero winter kill in 2009/2010.

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