Controlling Goosegrass in Cool- and Warm-Season Grasses
Elusine indica, commonly known as goosegrass, is an annual weed that rears its ugly head once soil temperatures reach about 60°F (at four inches) and will stick around all summer if it’s allowed to. We’ll briefly cover what goosegrass is before diving into how to control/prevent it in cool- and warm-season grasses.
Understanding Goosegrass
If you’re already pretty familiar with goosegrass, feel free to skip to the control section. In short, goosegrass is an annual weed that thrives in hot temperatures and water-saturated areas with thin turf, making it a common summer nuisance.
Conditions Causing Goosegrass
Weaker turf means a better chance of goosegrass. It’s a bit of an opportunist, taking advantage of compacted areas, thin areas, and areas without canopy cover. If an area is mowed relatively low, that can also make turf susceptible.
Goosegrass Identification
It can be identified through its stem, which appears silver in color, as well as its compressed sheath. The seedheads contain several spikes, which resemble a zipper to some. Goosegrass and crabgrass are both very similar in appearance, but goosegrass’ silver stem can assist in differentiating them.
Preventing Goosegrass
There’s one overarching problem that goosegrass causes, and that’s killing your turf by taking the necessary nutrients and water for itself. Not only is it an opportunist in the sense that it thrives in weak areas, but to add insult to injury, it also likes to compete with (steal resources from) the turfgrass it sprouts in. This means, that if left untreated, dead and bare patches will be commonplace.
There is, unfortunately, no “easy” way to deal with goosegrass. Each plant can contain up to 20 stems and carry 50,000 seeds, so simply mowing over them is like pouring accelerant on a fire in an attempt to put it out; They’ll come back in larger numbers next year. We need to go to the root of the problem. If we want goosegrass to stay gone, cultural practices and herbicides are the way to go.
Cultural Practices to Consider
There are some steps lawn care operators can practice that will help turfgrass remain healthy and resilient to goosegrass.
- Aerating to assist compacted turf
- Agronomic practices that can assist in enhancing turf health and/or growth, such as soil testing, correcting nutrient deficiencies, and mowing at the proper height
Both of these options can help bolster the strength and vitality of your turf, thus making it less susceptible to goosegrass. Lawn care operators may still encounter goosegrass, but sound practices will give turf a fighting chance.
Goosegrass Control Methods for Cool-Season and Warm-Season Grasses
Pre-Emergent Herbicides for Goosegrass Control
As mentioned, goosegrass germinates when soil temperatures reach about 60°F at a depth of four inches—about two weeks after crabgrass begins germinating. Apply pre-emergents when soil temperatures reach that level or use a phenological indicator like forsythia, which when fully bloomed will be a signal to apply pre-emergents two weeks after. A pre-emergent goosegrass herbicide will prevent it from growing, killing the seedlings right after they germinate.
While pre-emergent herbicides work well for many other types of weeds, goosegrass can be a bit tough to combat. Some products will feature the word “suppression” as opposed to “control” when they mention its effectiveness on goosegrass. The reason? Its germination period is pretty wide, and as such, many pre-emergent herbicides struggle to provide long-term control over the weed—though some are still up to the task, including these:
- Dimension 2EW (active ingredient: dithiopyr) Read Label
Dimension can be used on both cool- and warm-season grasses. Dimension should be applied at a rate of 0.5-0.73 fluid ounces per thousand square feet just before germination on established turf. A second application should be made six weeks after the first, and a third application can be made two to four weeks after the second application if late-season control is required. Do not use on certain fine fescue and creeping bentgrass types (see label for specifics).
Tolerant cool-season grasses: creeping bentgrass, Kentucky bluegrass, fine fescue, tall fescue, perennial ryegrass
Tolerant warm-season grasses: bahiagrass, bermudagrass, buffalograss, carpetgrass, centipedegrass, kiyukugrass, seashore paspalum, St. Augustinegrass, zoysiagrass
- ArmorTech Kade 4L (active ingredient: prodiamine) Read Label
Kade 4L can be used on cool- and warm-season grasses. Kade 4L should be applied at a rate of 0.48-1.1 fluid ounces per thousand square feet. One application should do the trick, however late-season control can be maintained with an additional application two to three months after the first. Do not apply to creeping bentgrass mowed at less than half an inch.
Tolerant cool-season grasses: creeping bentgrass (half-inch or higher only), Kentucky bluegrass, fine fescue, tall fescue, turf-type tall fescue, perennial ryegrass
Tolerant warm-season grasses: bahiagrass, bermudagrass, buffalograss, centipedegrass, kiyukugrass, seashore paspalum, St. Augustinegrass, zoysiagrass
- Ronstar Flo (active ingredient: oxadiazon) Read Label
A good option for more sensitive warm-season turfgrass, Ronstar Flo should be applied at a rate of 1.85-2.8 fluid ounces per thousand square feet in 0.75 to 3.5 gallons of water. Ronstar Flo is a liquid product that can be applied during late winter and early spring months before germination on dormant turf in the transition zone, typically alongside a product like Roundup. If an additional application is needed, wait four months after the initial application to do so.
Not for use on cool-season grasses.
Tolerant warm-season grasses: bermudagrass, St. Augustinegrass, zoysiagrass
In addition to the liquid product we covered, Ronstar also comes in a granular form, which should be applied to dry turf and watered in immediately. The granular version is also only intended for cool-season grasses as it has a high burning potential on actively growing warm-season grasses. Ronstar also comes impregnated in several fertilizers.
- Specticle Flo (active ingredient: indaziflam) Read Label
Another warm-season liquid product, Spectacle Flo controls goosegrass on established turfgrass. Apply at a rate of 0.138-0.23 fluid ounces per thousand square feet, depending on the type of turf. Mix with a minimum of one quart of water per thousand square feet to get the best results. If multiple applications are necessary on coarse or sandy soils, apply at a rate of 0.069-0.103 fluid ounces per thousand square feet for the first application and follow-up applications. Wait a month to a month and a half after the first application before making a second.
Not for use on cool-season grasses.
Tolerant warm-season grasses: bermudagrass, bahiagrass, buffalograss, centipedegrass, St. Augustinegrass, zoysiagrass
Post-Emergent Herbicides for Goosegrass Control
When pre-emergent application periods have passed, post-emergent herbicides are the next line of defense. Here are a few solid options to get rid of goosegrass after it’s germinated:
- Revolver (active ingredient: foramsulfuron) Read Label
Revolver is intended for warm-season turfgrasses and should be applied at a rate of 0.4-0.6 fluid ounces per thousand square feet for goosegrass control. For best results, make two applications of Revolver within three weeks of each other. A lower rate will control goosegrass weeds up to the three-leaf stage, while higher rates will be needed for more established plants. A third application can be made if regrowth takes place. Ensure that this third application is made before re-tillering. Revolver can be tank-mixed with several herbicides, including Ronstar.
Not for use on cool-season grasses.
Tolerant warm-season grasses: bermudagrass, zoysiagrass, buffalograss
Other types may be tolerant but manufacturer suggests a tolerance test.
- Dismiss Turf Herbicide (active ingredient: sulfentrazone) Read Label
Dismiss should be applied at a rate of 0.092-0.18 fluid ounces per thousand square feet for cool-season grasses and 0.18-0.275 per thousand for warm-season grasses. Dismiss should be applied during the pre-tiller stage. Goosegrass control will typically last for two months and multiple applications can be made.
Tolerant cool-season grasses: creeping bentgrass, Kentucky bluegrass, Poa trivialis, fine fescue, tall fescue, perennial ryegrass
Tolerant warm-season grasses: bahiagrass, bermudagrass, buffalograss, carpetgrass, centipedegrass, kiyukugrass, seashore paspalum, St. Augustinegrass, zoysiagrass
- ArmorTech Trione (active ingredient: mesotrione) Read Label
Also a pre-emergent option, Trione controls goosegrass before the four-tiller stage within two applications spaced two to three weeks apart from each other. Apply Trione at between 0.092 and 0.207 fluid ounces per thousand square feet (rates dependent on type of turfgrass, see label for details) as close to germination as possible. A surfactant can assist with control on actively growing goosegrass plants.
Tolerant cool-season grasses: Kentucky bluegrass, fine fescue, tall fescue, perennial ryegrass
Tolerant warm-season grasses: buffalograss, centipedegrass, St. Augustinegrass
- Acclaim Extra (active ingredient: fenoxaprop) Read Label
Apply Acclaim at a rate of 0.367 to 0.895 fluid ounces per thousand square feet in 100 gallons of water, depending on the growth stage the plant is in. Acclaim is specially designed to kill goosegrass (as well as crabgrass), and controls it up to the five-tiller stage. Some restrictions exist for warm-season turf; Acclaim is primarily for cool-season grasses, but can be used on zoysiagrass.
Tolerant cool-season grasses: Kentucky bluegrass, perennial ryegrass, fine fescue, tall fescue, Poa annua, creeping bentgrass (see special instructions for creeping bentgrass on label)
Tolerant warm-season grasses: zoysiagrass
Choosing Herbicides for Goosegrass
Whether you’re looking for products to combat goosegrass this spring or are simply seeking advice, your ATS rep is here to help! They’re here to help you prepare for, prevent, and get rid of your goosegrass for good.
