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Wednesday, December 7, 2016

Eliminating Bermudagrass from Lawns

Q. Can you help me and suggest how to eliminate Bermudagrass in my grass lawn please? It spreads like crazy. I’ve tried Round-up weed killer but no success. The roots are so deep.
Bermudagrass has stolons that creep or run along the top of the ground. They also have underground stolons that grow in a similar way.
A. Roundup will kill Bermudagrass but apply it at the highest rate allowed on the label. Roundup is systemic which means it kills the plant further from where it is applied, perhaps as much as 12 inches.
            You’re right. Plants with an extensive root system will only be “burned back”. They are burned back about 12 inches from the point of application. It needs to be applied several times as new growth pops up in new locations.
            Bermudagrass doesn’t like shade. It won’t grow in the shade of trees for instance. It is prevented from growing in a lawn because of the shade made by the lawn grass on the soil surface. As long as shade remains on the soil, the lawn grass does a pretty good job controlling it without chemicals.
Bermudagrass invasion because of line trimmer damage from edging badly
            Bermuda grass grows as a weed in a lawn when shade is gone. Shade disappears when the lawn dies or is damaged. Lawns die because of irrigation, disease or insect problems. When these dead spots appear in the middle of summer and the dead grass is removed, dormant Bermudagrass will grow. When lawns die in the middle of summer, do not remove the dead grass until it is time to reseed or sod these dead spots.
This is a weird shaped lawn to try and irrigate. You can't irrigate it well. Lots of wasted water. This lawn is during winter. The bermudagrass is brown because it is dormant. The fescue is green because it can handle cold. Bermudagrass invaded the weaker part of the lawn due to irrigation problems.
            Check the irrigation system. This is the most common reason lawns die or are damaged during our summer heat. Fescue remains in shady, wet spots. Bermudagrass invades dry areas in full sun.
Bermudagrass invading fescue lawn because it was mowed too short and the irrigation was not installed with even distribution of water
            Lawns are damaged when they are mowed too short. Lawns mowed below one and a half inches are too short and encourage Bermudagrass invasion. Line trimmers that cut the grass around sprinkler heads because the heads are too short damage the lawn and encourage Bermuda to grow in these locations.
            Spraying any present day weed killer in lawns that kills bermudagrass will either turn the lawn grass yellow or kill it. There is no magic bullet yet.

Keep bermudagrass from invading your lawn by:
  • mowing it tall to produce as much shade on the soil as possible
  • prevent damage like diseases or insects from killing the lawn in large patches so sunlight can trigger bermudagrass invasion 
  • Avoid edging a lawn with a "bevel" cut with a line trimmer. Use a steel edger or line trim without the bevel cut
  • When grass dies in the summer leave the dead grass in place to shade the soil surface until fall when bermudagrass grows poorly then fix the lawn

1 comment:

  1. As always Professor Emeritus Robert Morris is a wealth of knowledge!
    What I find works best in our rock filled yard is a combination of miners pick and elbow grease ;-)
    If I had a grass lawn that needed Bermuda Grass irradiation, I would probably invent some kind of boiling water injection needle. Maybe I can make an attachment for my portable rug cleaner. :-)