Round Up Ready Johnson Grass ?

Discussion in 'Pesticide & Herbicide Application' started by Atlantic Lawn, Mar 23, 2008.

  1. Atlantic Lawn

    Atlantic Lawn LawnSite Senior Member
    Male, from Outer Banks NC
    Posts: 938

    Bad news guys, I was reading online where Another weed resistant to Roundup has been found in Arkansas. Johnson grass resistant to glyphosate has been confirmed growing in a Crittenden County field in eastern Arkansas. So how does something like this happen ? Is it possible some of Monsanto's R/U ready products have run amuck ? I know there have been incidences where farmers have claimed that their corn was cross pollinated with a R/U ready strain, thereby erasing their family strain. Not good.
     
  2. rcreech

    rcreech Sponsor
    Male, from OHIO
    Posts: 6,020

    THIS IS NOT GOOD AT ALL!
    I haven't heard this yet, but it doesn't surprise me! J Grass is tough to kill with it's extensive rhizomes! We used to have a ton of it, but RR Beans and Corn has helps us a lot!

    Weed resistance isn't from anything other then plants that SURVIVED and/or didn't die from an application.

    THE KEY TO NOT GETTING WEED RESISTANCE IS TO ALWAYS USE A LETHAL DOSE OF CHEMICAL!

    When plants survive an application either from misapplication, weather conditions or UNDER APPLICATION, this is where offspring (seeds) can become "tolerant" to herbicides!

    Each time a weed "escapes" through an application they become more tolerant to the herbicide!

    We already have about a 6 or 8 weeds here in OH that are Gly resistant!

    Most farmers try to get by with as little chemical as possible due to cost. This can keep from getting a total kill and can cause resistance!

    EXAMPLE
    Say they need to go out with 22 z they will try and get by with 16 oz.


    We are using Roundup or generic Gly's about 2-3 times on every acre each year. This is another reason that resistance can occur. We used to use several different products each year and would change up modes of action.

    So long story short....it has nothing to do with cross polination or Monsanto, it is just the overuse of Gly and not using a lethal dose when applying!
     
  3. Brown's LC & L

    Brown's LC & L LawnSite Member
    Posts: 30

    I live in sw MO and I've got that crap in my yard. It sucks! I killed a few of them with round up, but the crap that's surrounded by fescue I haven't messed with because I don't want the dead spots.
     
  4. greendoctor

    greendoctor LawnSite Fanatic
    Posts: 8,826

    If you come to Hawaii, there are many invasive species that are inherently glyphosate resistant. I have seen weed populations shift to 75% resistant species or more in areas, especially on roadsides. Because the only herbicide ever used is glyphosate. That is all people in the business know. Most of the "landscapers" I know are unfamiliar with most of the herbicides I routinely apply. I blame the Hawaii DOA for that too. From 1996-2006, they managed to restrict the use of 2,4-D so much that no one bothered using it, much less import it into the state. 2,4-D is back and not a moment too soon. I also suspect that grassy weeds here are becoming resistant to glyphosate as well. The reasons rcreech mentioned are probably the cause here as well. If I am going to apply glyphosate via hand gun, the solution is at least 2.5%, so whatever I spray with it will die completely. Any normally susceptible weed not dead in 3 weeks is resprayed immediately. Other than that, I do not use very much glyphosate compared to the others in the business here. There is probably a bareground, contact, preemergent or systemic herbicide more suited to the situation and probably less expensive. So I need to keep 20 different herbicides with me. There is a cliche that fits "right tool for the job". I do not do landscape maintenance or vegetation management via RoundUp. It is costly in terms of time and materials, not to mention, when weeds do not die I can look quite the fool.
     
  5. Atlantic Lawn

    Atlantic Lawn LawnSite Senior Member
    Male, from Outer Banks NC
    Posts: 938

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