Q: I think you dodged the really hard questions in your series on fighting lawn weeds. Anybody can put on the pre-emergents to get those pesky, but controllable weeds. I have a more difficult problem: nutgrass. Tell the truth……is there really a way to kill nutgrass and not kill the azaleas in my beds, too?
A: I love a challenge and nutgrass (nutsedge) certainly supplies one! The chemical bentazon (click for sources) can be used in an azalea bed to control YELLOW nutsedge (not PURPLE nutsedge). You can’t do an over-the top spray – - you have to spray directly on the yellow nutsedge after it has emerged.
So how do you distinguish between the two sedges? You’ll have to examine the leaf tips closely to differentiate between yellow and purple nutsedge. Yellow has a folded, needle-like appearance at the tip while purple nutsedge leaves are a bit wider and they gradually taper to a point.
The chemical imazaquin (click for sources) can be used to control both yellow and purple nutsedge in many landscape situations. Read the label to be sure it can be used on azaleas.
The very best nutsedge control can be gotten with halosulfuron (click for sources). Most products that contain it are labeled for use on established woody ornamentals.
Both chemicals are absorbed by sedge roots so be sure to irrigate after application.
Since underground tubers can lie dormant for up to two years, one spraying will not control nutsedge. You have to be persistent about its control.
Nutgrass Control in the Landscape