Turf Magazine - April, 2012
Watch Out for Goosegrass
This troublesome weed often shows up after you've handled the crabgrass
The name goosegrass may fool you into not taking it so seriously on customers' lawns. Keep an eye out for it. This weed is a serious problem that lawn care operators and landscape contractors have to deal with. Property owners do not like goosegrass because it is unsightly in their lawns.
Because of unusually warm winter and spring temperatures so far in 2012, lawn care pros may be seeing goosegrass show up earlier on the lawns they maintain.
Identify goosegrass by its prostrate growth habit and by the shoots radiating from its white center.
PHOTOS COURTESY OF DR. DAVID GARDNER.
Goosegrass is mostly found in areas of turfgrass that are mowed short and are subject to high traffic or use. The weed is more common on compacted, poorly draining soils with thin stands of turfgrass than on well-maintained lawns with vigorously growing turfgrass.
Fortunately, green industry professionals have several proven cultural and chemical control options to keep goosegrass out of well-maintained turfgrass. Here are some strategies for controlling goosegrass in customers' lawns.
Before you can control this weed, or any weed for that matter, you must first correctly identify it. You must become familiar with how the weed lives, grows and the conditions favorable for its survival.
Goosegrass, Eleusine indica, is part of a group of summer annual weeds that germinate when the soil temperature reaches 60 to 65 degrees Fahrenheit. It needs moisture and light to grow. It grows well in compacted soils, can successfully compete with warm-season and cool-season grasses during the summer, and is more of a problem in established lawns.
You can identify it by its prostrate growth habit and its white center with shoots extending out in a wagon-wheel like appearance.
Measuring about .5-inch up to 2 feet tall in perfect growing conditions and left untreated, it's often confused with crabgrass. However, goosegrass, unlike crabgrass, is tufted at the base, with multiple ascending, protruding culms that feature alternate leaves. Goosegrass seedheads contain three to seven spikes that form at the tip of the seed stalk, and the seeds are attached in a zipper appearance on the spike. It also forms a tight rosette with a silver-colored center, another distinguishing difference between goosegrass and crabgrass.
Goosegrass spreads by seeds that germinate later in the season than other annual grasses, and could continue throughout the summer, sometimes as late as early fall.
Because it germinates much later in the season than other weeds, goosegrass can spell trouble for service providers that promise green, weed-free lawns. In fact, it often appears after preemergence herbicides have broken down and no longer offer effective control. "Because of this, split applications with preemergence herbicides may be more effective," says Dr. David Gardner, associate professor, turfgrass science, The Ohio State University. If there are just a few goosegrass plants on a customer's lawn, take them out with a pocketknife. Why treat the entire lawn when the problem is so easily solved?
Because it germinates later in the season than other weeds, goosegrass can spell trouble for lawn care pros.
Gardner says that lawn care pros should use integrated pest management (IPM) techniques to control goosegrass. IPM, of course, is based upon the establishment and maintenance of healthy plants. It's best not to seed when the soil temperatures and weather conditions are ideal for goosegrass to germinate. In the case of heavily compacted soils, which goosegrass prefers, stress the importance of aeration to customers. And, since goosegrass is found mostly where turf is kept short, raising the mowing height might help keep it at bay.
Chemical control is another option, and a preemergent application timed within two weeks after the temperature of the soil has reached a consistent 55 degrees Fahrenheit works best.
A postemergent herbicide can be used after germination. Gardner says there are three good options. For goosegrass in cool-season turf, either oxadiazon (Ronstar) or dimethenamid-p (Tower) are typically recommended, however Barricade and Dimension have activity, and then fenoxaprop (Acclaim) for postemergence control. As always, make sure to read and follow all labels before using herbicides or any chemical products on turfgrass or ornamentals.
Amy Hill is editor of Turf magazine. Contact her at email@example.com.