Knowledgebase
Is this crabgrass? Preemergence herbicide or not? #740989
Asked March 26, 2021, 7:04 PM EDT
Boulder County Colorado
Expert Response
Thank you for your detailed photos. Based upon what we saw in the photos we are leaning toward identifying this plant as a tall fescue variety. Please refer to this article from Perdue University. It is one of the sources we referenced in our research https://turf.purdue.edu/tall-fescue/. If the plant is a Tall Fescue, it is perennial grass so we do not recommend using a preermergent herbicide. Peemergents are designed to control annual grasses and weeds. A nonselective herbicide such as glyphosate can be applied to the tall fescue (see attached pdf for more information on herbicides). However, you will want to be careful and control applications of nonselective herbicides as it will kill the other desired grass species in your lawn. You can cover the the "weed grass" with a tall container with an open bottom and top to help prevent overspray into other lawn areas. Several applications may be needed for complete control. You can then reseed the treated area. You should wait to reseed 7 to 14-days after the final application. Follow directions for herbicide applications.
If you choose to use an herbicide, addressing your concerns to protect bees in your solution and limit bee exposure to herbicides, be careful to spot treat only in areas where needed and not near blooming flowers (avoid budding and flowering plants). It would seem not much is in bloom at this point. Another option would be to do a partial lawn renovation.
The attached documents provide more detail on herbicides and lawn renovation.
Let us know if you have more questions. Thank you for contacting us.