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Is it Crabgrass OR Dallisgrass?

July 1, 2014

I have gotten a couple of questions this week about weeds that sometimes are confused with crabgrass.  One weed that gets confused with Crabgrass this time of year is Dallisgrass.  Folks see Dallisgrass in their lawn and the first thought is that their Crabgrass preventer did not work.   Dallisgrass is a perennial grass that is common in the south and surrounding states to the north.  Since it is a perennial grass, it comes back every year from roots so a spring applied preventer to take care of annual grasses like crabgrass that grow from seed each year does not work.  Often the only choice is to kill this grass with a weed killer like Roundup.  The downside is that Roundup will kill all vegetation in the area that you spray, however you can seed that area a week later.  You may still have Dallisgrass next year because the plants produced seed all summer.  The seed heads provide the best way to identify Crabgrass and Dallisgrass.

On the other hand, if you have crabgrass, you can spray with Ortho Weed B Gon MAX plus Crabgrass Killer.   This spray is most effective on young crabgrass.  Click here for product info.

Dallisgrass seed head on left and Crabgrass seed head on right

Dallisgrass seed head on left and Crabgrass seed head on right (Click on photo to enlarge)

Dallisgrass can be confused with Crabgrass

Dallisgrass can be confused with Crabgrass (Click on photo to enlarge.)

Crabgrass

Crabgrass (Click on photo to enlarge)

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4 Comments
  1. Rick permalink

    Hi Ashton, I have a neighboor who has a big red maple tree that seems to be crazy fertile and the seeds from last season are taking to three inch seedlings by the hundreds all over my backyard, I mow tall in summer so my blade not chopping them down and is giving them a good foothold as of now…my question is, how do I go about the eradication process systemically to rid my lawn of these little buggers before they get a good taproot growing several feet down..please help. Thank you sir in advance

  2. Hi Rick
    Two suggestions: Drop your mowing height a little bit so your final cut is around 2-1/2 inches. They will not be able to tolerate repeated mowings. The other suggestion is to spray a few of them with Weed B Gon MAX plus Crabgrass Killer to see if you are getting any control. I would think that Weed B Gon Chickweed & Clover Killer would also do the trick. Hope one of these suggestions works out for you.

  3. Rick permalink

    Hi Ashton, in regards my maple tree seedling problem: you’re saying at the very minimum the constant mowing will expedite their demise? I really don’t want to use chemical control if I don’t have to. Thank you sir in advance

  4. Hi Rick
    Yes, I am thinking the mowing will do the trick. I do not have any personal experience with this kind of problem, however I believe this should work.

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