We are seeing and hearing about increasing problems with green and false kyllinga; both are very troublesome invasive weed species that have moved northward into New Jersey. Green kyllinga and false green kyllinga are very similar in appearance, and both are referred to as green kyllinga. Green kyllinga is very difficult to control once large mats form.
These weeds thrive under mowing and are prolific in areas that are poorly drained or frequently wet. If you do not have control over irrigation, encourage property owners to reduce irrigation when you find that the turf is frequently wet during dry weather; excess irrigation makes the problem worse.
Unfortunately for us, there are fewer herbicide options in the cool-season turfgrass market than in warm-season turfgrass market to our south.
The reports I have read indicate that preemergence herbicides provide no control of green kyllinga.
And there currently isn’t a commercially available postemergence herbicide that will provide excellent control of green kyllinga in cool-season turfgrass. Dismiss (sulfentrazone) is reported as providing good (80-90%) control and SedgeHammer (halosulfuron) is reported as providing poor (60% or less) control. Note that SedgeHammer is reported as more effective against false green kyllinga than green kyllinga.
Therefore, it is very important to understand that control is achieved with MULTIPLE applications of Dismiss or SedgeHammer. For example, two applications of SedgeHammer will suppress green kyllinga and probably not kill it unless it is small. Additionally, the herbicide label instructions for kyllinga must be followed or the products have no chance of working. For example, a non-ionic surfactant at 0.25% v/v must be added to the spray solution of SedgeHammer. Follow label instructions for herbicide rate, timing, and length of time between repeat applications.
Catching the problem early before the kyllinga mats become large, applying an active herbicide correctly, and being persistent are keys to achieving control.
Our colleagues in the Southeast were battling this problem long before us. You can view some of their information at these URLs…