eXtension

invasive non-lawn grasses

Asked July 27, 2017, 4:14 PM EDT

I've two very unique "grasses" that over past few years have taken toll on my carefully maintained lawn, regardless of several back-breaking bouts of ripping them out and re-seeding. Not sure what they are, what I should or can do to eliminate/reduce their impact. Since this interface allows 3 images, I'm breaking it into 2 separate email Qs: 1) the first I believe is a true grass, but rather than being straight, thin, soft on feet as other lawn grasses, this has broad, dark green leaves, and they've a tendency to cluster into "pin cushions". pulling out such a cluster, the roots are shallow, small ball-like thin fiber roots. I've attached a pic of these, "thick pin cushion". What specific grass is this, is it found in grass seed mixes, how can I reduce its spreading? thanks again

Thick_pin_cushion_1_300x300%2523
Thick_pin_cushion_2_300x300%2523
Thick_pin_cushion_3_300x300%2523

Ramsey County Minnesota

2 Responses

Thank you for the question. I think this weedy grass is tall fescue. The only way to kill it is to dig it out, watch for new seedlings, and promptly dig them out too. The only herbicide that will work is a non-selective one like Roundup or glyphosate but be careful with this because it will kill any other plants including the desired turfgrass species. Tall fescue is often included in grass seed mixtures and some varieties are showing promise as low input lawn grass but others can be weedy looking. If you overseed your lawn, make sure to read the grass varieties included in the package. Read about lawn weed and disease management here: http://www.extension.umn.edu/garden/turfgrass/

Thank you for contacting Extension.

thanks- I thought it was a type of fescue, and it is likely in some seed mixes. I try to avoid those.