Invasive Grass? #715977 - Ask Extension

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Invasive Grass? #715977

Asked August 21, 2020, 12:23 PM EDT

I have a new stringy grass taking over my lawn. It has long, strong, deep white roots. It sends out tentacles along the ground. I think I should kill it all. If so, how?

New Castle County Delaware

Expert Response

  It appears that your lawn has a batch of Bermuda grass. Don't know the extent but have forwarded a copy of a fact sheet from the University of Maryland with suggestions on managing your problem.

Bermudagrass
Cynodon dactylon bermudagrass

Life cycle

Perennial, warm season grass; also called wiregrass.

Growth habit 

Grows up to 2 ft. tall; goes dormant in winter and turns brown.

Reproduction

Spreads aggressively by strong, wiry stolons (above ground runners).

bermuda or wire grass in lawn

Conditions that favor growth

Mowing the lawn too short.

Management

  • Cultural practices (lawns) Maintain healthy, dense turf that can compete and prevent weed establishment.

  • Mechanical Management
    (In ornamental beds) small infestations can be dug out; must remove all parts of root. Do not rototill live plants.
    Hand pulling or using an appropriate weeding tool are the primary means of mechanical weed control in lawns. This is a viable option at the beginning of an infestation and on young weeds. Hand pulling when the soil is moist makes the task easier. Weeds with tap roots like dandelions or have a basal rosette (leaves clustered close to the ground) like plantain are easier to pull than weeds such as Bermudagrass (wiregrass) or creeping Charlie (ground ivy) that spread with stolons or creeping stems that root along the ground.

  • Chemical Treatment in Lawns
    Herbicides should be used as a last resort because of the potential risks to people, animals, and the environment. Be aware of  these precautions first.
    Perennial grasses are extremely difficult to control selectively in turfgrasses. A liquid, selective postemergent herbicide with the active ingredient Fenoxaprop can be used to suppress bermudagrass in lawns.
    Or, either use glyphosate (a non-selective herbicide) to spot treat or renovate the entire lawn. Renovation should be initiated in mid-to-late August allowing time for reseeding in September into early October. Weeds must be actively growing in August when glyphosate is applied. To improve control, water well and allow foliage to grow a week or two before treating. Apply glyphosate at the rate recommended for your weeds and do not disturb the foliage or roots for a week after application. Water to encourage any re-growth and treat again if new growth appears. But, be aware chances are good that the bermudagrass will return again in the future.  
    New grass can be seeded 7 days after treatment when you are sure the weedy grasses are dead.
Richard Pelly Replied August 22, 2020, 9:42 PM EDT
Thank you for your help.  We have killed all the bermuda grass, but now want to put down grass seed. Should we remove all the dead bermuda grass before seeding.  The dear stuff is really thick. Should be turn the soil over, rake and then seed or should we put dirt on top of the dead bermuda grass?  We were told not to till or turn over bermuda grass. But I think that is if the grass is still alive.  Is this true if we have poisoned it all and it is dead?
The Question Asker Replied September 30, 2020, 3:28 PM EDT
Hello,
Typically it can take 2-4 applications of a non selective herbicide to control bermudagrass.  I would spray it, at a minimum, one more time.  Then, after you have gotten a good kill and there is no green tissue remaining on the bermudagrass plants  you can begin to till and seed.
John Emerson Jr. Replied October 06, 2020, 8:56 AM EDT

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