I am planning on spot spraying with Glyphosate in the fall to get rid of some bentgrass patches:

If I wait a day or so can I overseed and fertilize? Or should I wait longer remove the dead grass/bentgrass with a rake and then overseed and fertilize? I think the product will start working in a few hours but need weeksto completely kill the bentgrass. Is core aeration a good idea before the seeding process. Thanks.

My grasstype is kbg and tall fescue.

  • 1
    What is your location? – kevinskio Feb 24 '20 at 13:36
  • Chicago suburbs. – justaguy Feb 29 '20 at 23:40

First, if you're going to use glyphosate, it's better to apply it during summer rather than waiting for slowed down growth in Fall. Glyphosate works best on strongly growing green plants (including grass) so is best used during late spring and summer for best effect.

It will take two weeks for the patches of grass you don't want to be killed off at the root - some more persistent grasses may need a second application, see here https://homeguides.sfgate.com/glyphosate-kill-lawn-101334.html. Once it is dead, pull out what you can and then aerate prior to overseeding.

  • Thank you very much :). – justaguy Feb 23 '20 at 21:48

You can kill bent grass selectively with Tenacity. I use it on its cousin, nibble-weed. Tenacity is the synthesized chemical Mesotrione, which is naturally occurring in the bottle-brush plant. It is also amazing as a pre-emergent, as you can spray on bare ground after seeding new ground. Weeds are suppressed, yet the KGB still germinates. I used it to battle quack-grass in my suburban yard.

It also controls many other weeds, but it does not kill per se. It interrupts the plants ability to breakdown the byproducts of photosynthesis, thus halting that process. The weeds end up losing their green color and go bleach white; they starve to death. It takes a couple of treatments but is selective. I love the stuff. The only issue I have had is repeated treatments in high heat can damage the turf, but nothing a good season won't repair.

  • I'm going to add that the organic plant/lawn healthcare company we work with on many estate properties uses Tenacity to great effect. I'll also say that there are so many golf courses in the area that bentgrass is always getting into lawns, so it is an endless battle. – That Idiot Feb 25 '20 at 21:20
  • Technically, the chemical is synthetic, but it does exist in nature. This makes me feel better about using it. Every little sliver of bentgrass can root into it's own crown. Control is tough, but it's exactly why courses use it on greens for the self healing property. Mow, top dress, mow, top dress. – Evil Elf Feb 26 '20 at 12:56
  • I like tenacity, havent used it much, but it works great.... I have a 20k front yard and 3k back yard so glyphosate is more economical. I use tenacity 0n the 3k and it looksgreat. Thank you :). – justaguy Feb 29 '20 at 23:49

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