April advice for recovering a lawn with possible disease infestation

Asked March 26, 2019, 4:53 PM EDT

Can you identify the cause of the spots seen on the picture attached? This picture was taken in late March. What is the best way to treat this problem and i am also looking for optimal fertilization suggestions? This portion of the lawn is in bright sun (no shade) during the day.


Howard County Maryland

1 Response

We can't tell for sure from your photos but would guess it is a either a perennial grassy weed called Nimblewill: https://extension.umd.edu/hgic/topics/nimblewill
Or annually re-seeding Japanese stiltgrass: https://extension.umd.edu/hgic/topics/japanese-stiltgrass Take a look at the photos on those pages and compare.

Both are not as noticeable once it greens up later in the season. Japanese stiltgrass is controlled by putting down a pre-emergent like those used for crabgrass but a little earlier. Nimblewill is best controlled by completely killing the patches with non-selective herbicide containing the active ingredient glyphosate in the summer, followed by overseeding or renovation in the fall.
Here is our lawn page: https://extension.umd.edu/hgic/topics/lawns

Lawns are best fertilized in the fall, and the only way to know what fertilizer is needed in what quantities is by having a soil test done.
Here is our soil testing page with all the information you need, from how to take a good sample to a list of regional labs who can complete the analysis for you:
It is not expensive and it doesn't take long.