Japanese stiltgrass

Asked March 16, 2017, 11:52 PM EDT

Japanese stiltgrass has invaded my lawn as well as plant beds. Last year I did my best to weed the beds and keep the lawn mowed. What would be the best practice to control it in the lawn? Would a preemergent weed and feed application touch it? I bought a bag of 18-0-4 fertilizer that contains .38 prodiamine for weed control but wonder if that is a suitable product or if you would recommend something different. Also, when should something be applied...spring or fall or both? Is temperature a factor? I appreciate your suggestions because I have large patches that are crowding out fescue grass.

Harford County Maryland stiltgrass lawn weed

1 Response

Japanese stiltgrass is an annual weed, so it dies back in the winter and seeds germinate to grow anew in the spring.
So yes, a spring application of a preemergent can help, and the timing is now.
We suggest finding a preemergent that is NOT part of a 'weed-n-feed' fertilizer, as fall is a better time to fertilize lawns here. You can find the preemergent herbicides like pendimethalin or prodiamine on their own, with maybe a very small amount of 'carrier' nitrogen. (like Halts).
Here is our page on Stiltgrass and it's control: http://www.extension.umd.edu/hgic/lawns/lawn-weed-identification

Using what you have there could be used in the fall, and would prevent weeds that are winter annuals like hairy bittercress (see our lawn weed gallery here: http://www.extension.umd.edu/hgic/lawns/lawn-weed-identification) and others that germinate in the fall.