Keep crabgrass and goosegrass in check

How lawn care operators attack crabgrass and goosegrass often depends on turf and weed type. (Photos: James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org)

Crabgrass and goosegrass are notorious weeds lawn care operators (LCOs) must tackle in the summer, but management of these two turfgrass foes is different. Goosegrass will settle into open spots caused by disease, pests, shade or even foot traffic, says Gilbert del Rosario, turf and ornamental western sales and market development leader for Corteva Agriscience. It’s a similar situation for crabgrass. Follow these tips from experts to keep the weeds at bay.

What to apply

As crabgrass and goosegrass germinate this summer, a postemergent herbicide application may be necessary.

“Postemergent goosegrass control is often more difficult than crabgrass — there are fewer options and repeat applications are more likely to be necessary,” says Aaron Hathaway, technical services manager at Nufarm.

For goosegrass, fenoxaprop-ethyl is an option in zoysiagrass, and topramezone is an option in cool-season turf and a few warm-season species, Hathaway says. In warm-season turf, some leaf bleaching can occur with topramezone, depending on the turfgrass. Other postemergent herbicides with foramsulfuron and combination products that contain ALS inhibitors can provide control, he says.

For postemergent crabgrass control in cool-season turf, Hathaway says to look for herbicides with active ingredients fenoxaprop-ethyl, topramezone and mesotrione.

In the early postemergence stage of crabgrass, del Rosario says that dithiopyr is an option, and although it is technically a preemergent herbicide it can provide residual control for several months.

For warm-season turf, Hathaway says LCOs should use a product with quinclorac or a combination of products with ALS inhibitors for postemergent crabgrass control in Bermudagrass or zoysiagrass. Hand pull weeds or suppress outbreaks with imazaquin in St. Augustinegrass. Hathaway says a postemergent application with a combination of products with ALS inhibitors works well for centipedegrass.

Del Rosario says LCOs should understand an herbicide’s potential for drift and avoid applications in windy conditions or in hot, dry conditions.

“It is best to read and understand the prospective herbicide label to determine the right use rate when it is best applied, if an adjuvant is required and if it is safe on the desired turf type,” del Rosario says.

Cultural practices

Cultural practices, when paired with preemergent and postemergent herbicides, can help manage these weeds.

Encouraging clients to raise the mowing height, Hathaway says, can help reduce germination of both crabgrass and goosegrass and help the turfgrass outcompete the weeds.

Del Rosario says cultural practices such as fertility programs, minimizing compaction and proper irrigation will help keep the turfgrass stand dense and actively growing.

Think about fall

Although we’re in the thick of summer weed control, del Rosario says now is time to focus on preemergent treatments for next year.

“Take note of how busy it is,” he says. “Would an early-season preemergent application when it is less busy make more sense to the business? Make note of the scheduling and labor challenges and look for ways that herbicide tools may be used to spread out the workload.”

Preemergent herbicides may provide an application window to combat different growth stages of the weed and provide residual control, he says.

Hathaway says contractors need to understand the potential for herbicide resistance, especially with preemergent treatments for goosegrass.

“Think about rotating chemistries and cleaning up preemergent breakthroughs with postemergent herbicides to limit resistance issues,” he says. “Use preemergent herbicides as your first line of defense, use cultural practices to produce a healthy stand of turf and remember to find a specific herbicide that is safe on your specific turf species.”