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Give Yourself the Edge in Managing Sedges in Lawns and Landscape Beds
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Welcome to The Turf Zone Podcast. This episode features the article “Give Yourself the Edge in Managing Sedges in Lawns and Landscape Beds” written by Jeffrey Derr and Adam Nichols.
Sedges are major weed problems in turf and landscape ornamentals, as well as in crop production, including container- and field-grown nursery crops. Although there are annual sedges that occasionally are problems in these areas, the major problems are perennial species. Having an understanding of their taxonomy and life cycle will aid you when developing a control program.
Sedges are monocots, which mean they have one seed leaf when they germinate. Grasses are also monocots, but they are in a different plant family, the Poaceae, as opposed to sedges, which are in the Cyperaceae or sedge family. So do not use the term “nutgrass” when referring to yellow nutsedge. Yellow nutsedge is not a grass and it is confusing to use a term that implies that it is a grass. You may ask “But what about broomsedge – isn’t that a grass?” Well, yes, but that is a topic for another article!
The distinction between grasses and sedges is especially important when discussing chemical control. Most of our sedge herbicides do not affect grasses and most of our grass herbicides do not affect sedges. Here is some help in separating grasses from sedges. Grasses have round or flattened stems, generally have a ligule (either a membrane or fringe of hairs where the leaf blade meets the leaf sheath), and have two-ranked leaves (leaves appear from 2 sides of the stem). Sedges have triangular stems (sedges have edges), lack a ligule, and the leaves are three-ranked (come out from the three sides of the stem. When I taught the weed science class, I would slip in yellow nutsedge when we had the lab on grass identification to see what the students would do with it. They obviously struggled with it when trying to fit yellow nutsedge into a grass key.
Major species:
The most common sedge infesting turfgrass and ornamental beds is yellow nutsedge, a weed that occurs throughout Virginia. Yellow nutsedge is a perennial that spreads primarily through vegetative means. Rhizomes produce roughly ¼ to ½ inch long, tan to brown tubers in summer and fall. These tubers overwinter and then send up new shoots in the spring. Above-ground parts of the plant die with a killing frost. Although yellow nutsedge will produce seed, it does not appear to be an important factor in the spread of this species. Leaves are shiny and yellowish-green.
Purple nutsedge, similar to yellow nutsedge, also is an herbaceous perennial that spreads by tubers and rhizomes. Leaves of purple nutsedge tend to be darker green than yellow nutsedge. The tubers are the same size as those for yellow nutsedge but are dark brown or purplish brown. Tubers of purple nutsedge have a bitter taste while those of yellow nutsedge have a sweet or almond-like flavor. Purple nutsedge has a purplish-brown seedhead, while yellow nutsedge has a, well, yellow seedhead. In a turf situation, however, you probably will not see the seedheads of either species, especially in frequently mowed sites, but seedheads would develop in ornamental beds if uncontrolled. Yellow nutsedge leaf blades have a long, sharp point while purple nutsedge has a blunt tip. However, this also may not be apparent in a mowed situation.
Why is it important to tell yellow from purple nutsedge? Certain herbicides, such as bentazon, mesotrione, metolachlor, and sulfentrazone, are more effective on yellow than purple nutsedge, while other products work well on both species, such as halosulfuron. Purple nutsedge is predominantly a problem in southeastern Virginia. Purple nutsedge is found predominantly in the South while yellow nutsedge is found essentially throughout the contiguous 48 states.
Another sedge group that has spread rapidly in Virginia is kyllinga. To me, kyllinga in bloom looks like a green ball about the size of a pea sitting on 3 green leaves. There are both annual and perennial kyllinga species but the ones of greatest concern are the perennials green and false green kyllinga. Kyllingas will also have a triangular stem but lack the tubers formed by yellow and purple nutsedge. The perennial kyllingas spread not only by rhizomes, but readily by seed, probably a factor in their spread, as they can flower below mowing height. We grow false green kyllinga by seed for our trials. Chemical control for kyllingas is very similar to that for yellow nutsedge.
The primary annual sedge that I have seen in turf areas is compressed sedge. Rice flatsedge is an occasional annual weed in container production. We had fragrant flatsedge come in as a contaminant in plants I purchased from down south and it has been the most aggressive grower of the sedge species we have evaluated. These three sedge species spread strictly by seed and thus are easier to control than perennial sedges.
Factors favoring growth of sedges
Sedges grow best in warm temperatures, moist soil, and high sunlight. I usually do not see yellow nutsedge emergence until early April or later, depending on how quickly it warms up in the spring. Yellow nutsedge grows best in May through August, similar to that for bermudagrass. The sedges are not necessarily that much more competitive than turf species, but they can rapidly take advantage of any openings in the canopy. I always remember one of our former students who was working on halosulfuron when it was being developed. He had trouble getting yellow nutsedge to establish in his Kentucky bluegrass plots but where he killed out the bluegrass for his plot borders, he saw a nice straight line of yellow nutsedge in the killed strips!
One problem with managing yellow and purple nutsedge is tuber dormancy. Not all tubers send up shoots at the same time. Some shoots will emerge in May, some in June, and some in July. Also, some tubers may not send up shoots until the following year or two. Most tubers are viable for only 2 to 3 years, but some can remain viable for 10 years or longer. So if one has an established stand of yellow or purple nutsedge they wish to eradicate, it will be a multi-year project. Even if you achieve 100% control in a season, you probably will see nutsedge emergence the following year.
Cultural Control of sedges
Maintaining a thick stand of turf will help restrict the development of sedges, especially in the spring when nutsedge shoots emerge from the underground tubers. Overseed and fertilize cool season grasses in the fall to have a thick, competitive stand when sedges resume growth in late spring. Avoid scalping turf as this opens up the canopy for invasion by sedges, crabgrass, and other weed species. Control insect and disease pests to prevent thinning of the turf. Avoid overwatering turf and ensure proper soil drainage to prevent excessively wet soil. Monitor new sod or ornamental plant installations to insure that nutsedge or kyllinga has not hitchhiked along with the sod or nursery plants.
Avoid any stress that adversely affects turf growth. I always think of a turf situation I was asked to investigate. They had applied fluazifop in a backpack sprayer for bermudagrass control in tall fescue. Not only was the bermudagrass controlled, so was the tall fescue. It is hard to determine a spot-treatment rate of fluazifop that will be safe in tall fescue. They reseeded and ran the irrigation frequently in summer, which led to an excellent stand of compressed sedge. The cause of the sedge infestation was the initial turf damage caused by improper herbicide application.
Yellow nutsedge is hard to control using hand weeding as plants can break at the soil line, leaving the underground tubers and rhizomes. Tilling can spread the tubers, increasing the area of infestation.
Chemical control of yellow nutsedge
Learn the active ingredients listed in Tables 1 and 2 (available in the May/June 2026 issue of Virginia Turfgrass Journal on www.theturfzone.com). Some of these herbicides are sold in combination with other herbicides but I have only listed single active ingredient products that we have tested. There are a number of combination products that contain a sedge herbicide but also other herbicides for either broadleaf or grass control. For example, Sublime contains mesotrione, triclopyr, and dicamba. If you know the active ingredients, you will have a good idea as to how that combination product will perform.
1). Preemergence control in turf
I frequently am asked about the availability of preemergence herbicides for nutsedge control. Actually, I prefer postemergence applications for yellow nutsedge control since this weed usually occurs in patches and thus fits well into spot-treatment programs. The problem with a preemergence application is that one would have to treat the entire lawn since the chemical must be applied prior to sedge emergence, unless one mapped out the previous year exactly where nutsedge was growing in a turf stand. The other reason favoring postemergence control of nutsedge is that few preemergence chemicals are available for turf use. Some postemergence herbicides, such as halosulfuron (SedgeHammer, Prosedge), mesotrione (Tenacity), and sulfentrazone (Dismiss) do have a degree of preemergence control, but I consider that a bonus following postemergence application.
In bermudagrass, zoysiagrass, and certain other warm-season grasses, there are registrations for Pennant Magnum, Tower, and FreeHand for residual control of yellow nutsedge. These herbicides are much more effective on yellow compared to purple nutsedge and have generally short residual control. Also, we have seen delayed greenup with this group. However, we do use these products in ornamental beds.
2). Preemergence control in ornamental beds
We do focus on preemergence herbicides in ornamental beds due to general lack of selective postemergence herbicides for overtop use. Products to consider include metolachlor (Pennant Magnum) and dimethenamid (Tower), both of which are oil-based formulations and thus should be applied as a directed spray, as well as the granular herbicide FreeHand, which contains dimethenamid plus pendimethalin. FreeHand is probably a good choice for most landscape bed situations. It can be applied to certain annual flowers (but not begonia) and a wide range of perennials and woody ornamentals. Apply in March or in early April in eastern Virginia and a little later in western parts of the state. Reapply about 6 or 8 weeks later to extend the length of yellow nutsedge control.
3). Postemergence control in cool-season turf
I have divided up the herbicides to ones registered for use in tall fescue, Kentucky bluegrass, and perennial ryegrass and those registered for use in bermudagrass and zoysiagrass. I have listed the trade names we have tested. You may find other trade names for these active ingredients. The two tables cover the primary treatments available for sedge control in turfgrass. The same herbicides that are used for yellow nutsedge control in turf are utilized for kyllinga control. MSMA is not included as it is only registered for use in golf, sod production, and highway rights-of-way.
Bentazon and sulfentrazone are the fastest-acting chemicals in this group, probably because they predominantly have a contact action. Injury symptoms in yellow and purple nutsedge can be seen within a few days of application, especially when applied under warm conditions. Repeat applications will generally be needed sooner for bentazon than the other products. For example, a second application of bentazon is generally made one to two weeks after the first one. We have found pyrimisulfan to be the slowest acting herbicide in this group of chemicals, with halosulfuron and imazosulfuron intermediate in speed of action. Of the pyrimisulfan products, we have seen better yellow nutsedge control with Arkon compared to Vexis.
One benefit of mesotrione is that it can be used at seeding time or on young stands of cool-season turf. The other products generally can only be used on established turf.
We did a trial last year looking at the impact of simulated rainfall on yellow nutsedge control in our rain-out shelter. When we irrigated one hour or one day after a sulfentrazone application, we saw effective yellow nutsedge control, but control decreased when irrigation was withheld until one or two weeks after application. It appears root uptake is an important component of sulfentrazone’s activity against yellow nutsedge and thus rain or irrigation is needed within a week after application. Halosulfuron gave excellent yellow nutsedge control, even when irrigation was withheld until one or two weeks after application.
We often grow yellow nutsedge in containers for control trials to supplement what we do in the field. In one container trial, we collected yellow nutsedge tubers that formed after herbicide application. Tubers were much smaller when plants were treated with halosulfuron or pyrimisulfan compared to sulfentrazone. This should result in less competitive yellow nutsedge in subsequent growing seasons.
Bentazon and sulfentrazone are much more effective on yellow compared to purple nutsedge. This shows why we need to identify these two species. One needs to address purple nutsedge differently than yellow nutsedge. Halosulfuron and imazosulfuron are equally effective on yellow and purple nutsedge. Work by other researchers suggests imazosulfuron is the most effective treatment for false green kyllinga (Dr. Matthew Elmore, Rutgers University). We also have seen good control of false green kyllinga with imazosulfuron.
Sulfentrazone is sold in combination with other herbicides, such as with prodiamine under the trade name Echelon. Sulfentrazone is a component of combination herbicides Surge, Q4Plus, and Avenue South but the concentration of sulfentrazone is lower than in Dismiss, resulting in more suppression than control of yellow nutsedge.
One will generally add some type of adjuvant to these postemergence herbicides. Nonionic surfactants are generally recommended for most of these chemicals but check the label for instructions on adjuvant addition. Addition of a methylated seed soil or crop oil concentrate may increase toxicity of certain chemicals to nutsedge, but also may increase the potential for crop injury especially under hot, humid conditions. Read the product label for specific directions on adjuvant use.
Postemergence control in bermudagrass and zoysia
A number of the products are the same for warm-season grasses as for cool-season grasses, but mesotrione is not listed as it injures bermudagrass. Certain products used for removing cool-season grasses from warm-season turf are effective for controlling sedges are added, including flazasulfuron, sulfosulfuron, and trifloxysulfuron. Aethon was added to the warm-season list but not cool-season turf as it also contains penoxsulam, which can
injure tall fescue. Along with pyrimisulfuron, imazaquin, flazasulfuron, sulfosulfuron, and trifloxysulfuron are slower-acting herbicides since they are systemic in plants and travel to the growing points. Imazaquin has been less effective in our trials for yellow nutsedge control than the other herbicides listed. Flazasulfuron, halosulfuron, sulfosulfuron, and trifloxysulfuron will control both yellow and purple nutsedge.
Postemergence nutsedge control in ornamentals
Around trees and shrubs, directed sprays of bentazon, halosulfuron, or sulfentrazone can be applied for yellow nutsedge control. Minimize contact with the leaves of the ornamentals. We do not have selective herbicides that can be sprayed overtop of ornamentals plants for sedge control. Nonselective herbicides, such as diquat, glufosinate, or glyphosate can be applied for sedge control if kept totally off ornamental plant leaves. A common question I receive is how to control emerged yellow nutsedge in liriope beds. We have seen injury from bentazon and halosulfuron, especially in variegated types, although plants outgrew the damage, and we observed reduced flowering from halosulfuron. Best to utilize preemergence applications of FreeHand to minimize the need for hand weeding or postemergence applications.
Jeffrey Derr and Adam Nichols are based at Virginia Tech’s Hampton Roads Agricultural Research and Extension Center in Virginia Beach.
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