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St. Augustine - Killing Weeds

Discussion in 'Pesticide & Herbicide Application' started by JamesTWebb, Jun 22, 2009.

  1. JamesTWebb

    JamesTWebb LawnSite Member
    Messages: 4

    Can anyone recommend something to decrease, and eventually remove, weeds in St. Augustine grass?
  2. gregory

    gregory LawnSite Bronze Member
    Messages: 1,081

    manor is a good one this time of year...
  3. JamesTWebb

    JamesTWebb LawnSite Member
    Messages: 4

    I am unfamiliar with manor. Please explain...
  4. gregory

    gregory LawnSite Bronze Member
    Messages: 1,081

    what would you like me to explain? you can buy manor at lesco pro source one or almost any fertilizer place...
  5. JamesTWebb

    JamesTWebb LawnSite Member
    Messages: 4

    Thanks for the help
  6. gregory

    gregory LawnSite Bronze Member
    Messages: 1,081

    no problem.. read the label... need anything else let me know....
  7. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Messages: 2,254

    Manor is metsulfuron and is sold under the new name of "Mansion" at Lesco. You can still get it from PBGordon under the name of Manor. It is a very powerful herbicide and must be correctly applied. Most of your warm seasoned grasses are not tolerant of things like 2-4D. Even "Southern Speedzone" effects them greatly. It is the Dicamba in them that harm the grass. So be careful.
    If you have Dollarweed, Nutsedge, Green Kyliinga, etc. a good product is "Image" It is sold by the pound and is a water soluble product at Lesco or Pro-Source. You can also buy it in a hose end applicator bottle at Lowes which will cover about 6000 sq feet. Make sure that you grass is not stressed (Needing Water or Fertilize), No drought conditions and growing vigrously before using it. It needs to be water into the ground withing 7 seven days of application. READ THE LABEL!!!!!!!!
    Finally a really good product is Atrazine, but I caution you that it shouldn't be YOU used now. It's best to use it during the cooler months. Read the label also. Atrazine can be used by pros during the warm weather if applied correctly. Try the Image in the hose end bottle for now. The hose puts down enough water to be safe BUT please apply it evenly.
    What weeds are you battling? One herbicide will not kill all weeds and most of us use a combination of things or even multiple applications.

    Be sure that you read those label and mostly follow them!!!!! A whole lawn can be killed quickly with the wrong stuff.

    You best defense should be a strong offense to make your lawn so thick that weeds cannot complete. That is done with the proper fertilization and micro-nutrient mix. You do realize that St. Augustine needs 1lb of Nitrogen per 1000sq. ft. every month during the active growing season.
  8. gregory

    gregory LawnSite Bronze Member
    Messages: 1,081

    good job roy...

    some of the st augustine guys here on the board are RIC, GREENDOCTOR, AND RALMAROAD... i am sure there are others but these 3 have helped me alot.... use the search bottom on top and you will learn alot just by reading search post by there names or names in it.....
  9. JamesTWebb

    JamesTWebb LawnSite Member
    Messages: 4

    Currently, the weeds I am struggling with are crabgrass, ryegrass/bermuda, torpedo, and nutsedge. There are others, but are minor compared to the others mentioned previously.
  10. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 10,003

    I will give herbicide advice after I know the fertilization, mowing and irrigation practices. For one thing, st augustine needs 3/4-1lb of nitrogen per month and up to 1/2 lb of potassium. Phosphorus is to be applied if the need is indicated by a soil test. Soil pH should also be between 6.0-7.0, no higher or lower. Iron and manganese are very beneficial for lawns, those should be applied with fertilizer. I also want to see st augustine mowed with a sharp blade at 3-4" weekly. No scalping with weedeaters or mowers set too low. I have had to tell "landscapers" that they will owe their client lots of sod if they do not raise their decks and stop using the weedeater to shave the grass down to the dirt. In dry conditions, the lawn should be watered according to how well the soil retains water. In heavy soils, 1-1.25" of water applied once a week will work. On sandy soils, that changes to 0.3-0.4" applied every other day. Do not ever water at night, not even in hot weather unless you would like a lesson on fungicide use and application.

    Once you have the above issues in order, the weeds are next. Crabgrass, nutsedge and ryegrass are killed by Image. Listen to how RAImaroad is telling you how to use it. Do it wrong and it will kill the grass instead of the weeds. The bermuda and torpedo grass are best treated with RoundUp. I like to use a nylon bristle house paint brush to wipe on a 30% solution on unwanted grasses. If the lawn is on a good fertilizer program, the bermuda and torpedo will stick up above the lawn. That is when you brush just the weed grasses. I suggest putting in some turf marking dye or even some food coloring in the mix to indicate what has been brushed. I know this sounds like a PITA to do, but a hand sprayer of RoundUp will cause enormous dead patches in the lawn beyond where you sprayed. Those dead patches will probably grow an incredible amount of weeds as well unless you prep and re sod each patch as soon as it dies. I rather spend a few more minutes selectively treating unwanted grasses rather than burning holes in a lawn.

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