Lawn Quackgrass elimination methods

Asked August 9, 2018, 3:44 PM EDT

Using Roundup, what application methods would you recommend to kill Quackgrass in selected patches in a lawn without affecting the grass?

Stearns County Minnesota

1 Response

The quick answer is there no 100% effective way of doing this. If you are very careful, using a hand sprayer, you can largely direct the Round Up on the quack grass with minimal damage to surrounding grass. I know this for a fact having done it many times. But, still, there will be some over spray. It will be hard to avoid. But there is a slight benefit in doing all this. Once your quack grass has died from the Round Up, you will need to replace the turf where the quack grass once existed. So one way or the other you will be faced with some reseeding. Put the Round Up on the quack grass right now. It is an active growing phase and application of Round Up at this time will get the glyphosphate directly into the roots, very effectively killing the quack grass. After the first Round Up treatment, the quack grass should start to yellow within four or five days. If it does not, a second treatment may be necessary. Be cautious in using "old" Round Up (left over from 2016 or 2017). It may no longer be effective. Once the quack grass has yellowed and died, vigorously rake up the dead vegetation. Then water the areas well over a period of ten days or so. This will dilute any residual Round Up still in the soil. Spread a thin (an inch or so) of good top soil on the area and reseed with your desired grass. Again, water well. However please be aware that now the quack grass is spreading seed that will germinate next spring. So in these same areas, spread from pre-emergent herbicide next spring before any greening-up occurs. Probably late April or early May. However still be prepared to see some quack grass in 2019. It is a tough customer and does not disappear quickly. Complicating this is that quack grass seed may be blown into your yard this fall from your neighbors.

Good Luck.