Question of the Week Number 1: February 7, 2019
“What can I use to kill these weeds in my lawn?”
Posted on Facebook last week by friend G.E., but I’m asked similar questions several times daily.
These are cool-season grassy weeds. That means that they germinate in the fall, establish roots and some top growth over the winter and start growing aggressively with the warm weather of late January and on into February (earlier in South Texas).
Annual bluegrass (Poa annua) will begin showing seedheads soon. It’s a fine-textured weed that shows up just about everywhere.
Rescuegrass goes to seed in February in South Texas, later in northern counties. It’s one of the most robust of our winter weed grasses.
There are several common winter grasses, but rescuegrass, annual bluegrass and ryegrass are at the top of the list. I’m getting questions everywhere I turn right now about them. I’ll give you all I have to offer.
• There is no weedkiller available to us that will kill cool-season annual grasses growing in an established lawn without damaging the permanent lawn (bermuda, St. Augustine or zoysia).
• Your only way of dealing with these weeds is to apply a pre-emergent herbicide such as Dimension, Balan or Halts granules the last week of August or the first week of September. That’s before the grasses’ seeds sprout. Once they germinate and start growing you’ve basically blown it for another whole year. (Sorry for the blunt honesty.)
• At this point I would suggest dropping your mower down one notch and scalping the grassy weeds off. It won’t kill them, but it will make things look better. It will also allow the sun’s warming rays to help your turfgrass green up quicker so the weedy grasses won’t be so noticeable. They will run through their life cycles by mid-April as the weather turns warmer. Just don’t forget that pre-emergent next time around!