How can I kill Nutsedge? Exactly what is it and is Sedgehammer any good?
Nutgrass is some crazy stuff. It's one of the worst family of weeds to deal with because of how it propagates. When you try to pull a nutsedge out of the ground you unknowingly cause hundreds of tiny seeds, or nuts, to be put back into the dirt, only to rise and cause you to repeat the process. This weed is evil, and it needs to be killed.
Nutsedge is not a grass, it is purely a weed. It provides no benefit whatsoever to your lawn or turf. There is only one way to kill this weed, and that is with a specialty herbicide designed only for nutsedge type weeds. For a long time people have confused this weed with being crabgrass and so they grab the trusty RoundUp QuikPro, or some other form of generice glyphosate and figure they can spot treat the weed. The problem is that RoundUp is not designed to kill the "nuts" or seeds that are in the ground and therefore this perennial problem continues to manifest itself leaving the lawn caretaker befuddled and on the brink of self-mutilation (yes, some people take their lawns/turf that seriously).
The picture the the left is of Yellow Nutsedge, the other most common form of sedge being the Purple Nutsedge. Now, one of the "natural" things that you should do to control nutsedge, plus it's just plain simple a good idea from the get go, is to keep your drainage under control. By that I mean it's the water logged grasses that give nutsedge a foothold in the first place. The mere fact that you have a nut sedge problem is evidence of too much water being present. That can be from poor drainage, or too much sprinkler action. Whichever it is, get it under control man, or you're just giving this weed the environment it thrives in.
The worst part about the whole water logged issue is that once the nutsedge is in, and you get your irrigation or drainage issue fixed, the nutsedge isn't going anywhere. Once it's established itself, it's established. Many people have made the mistake of taking the landscapers advice and fixing the drainage issue, thinking the nutsedge problem would disappear. They learn all to well that they inadvertently created a problem that they are stuck with until dealt with selectively.
Some people will suggest you pull this weed. Fine, go ahead and pull it and post back here in a week how many took its place. DO NOT pull this weed WITHOUT treating chemically with a selective nutsedge weed killer. Also, not sure how technical you want to get here, after all, we're just chewing the fat about this common problem we have, but technically what we refer to as the "nuts" that this weed deposits into the ground are not nuts at all, but something called "tubers". Yeah, I know, "tubers", silly name. I like "nuts" better, but it's not up to me. So whether you call them tubers or nuts, let's get down to how do we kill them?
Remember, these are perennial plants and die off as the temperatures drop and we head into fall, however, tubers survive in the soil ready to spring up next year. Obviously the best way to deal with this weed is to not have it in the first place, but I guess we'll have to assume that we're past that wistful point, so we are forced to deal with this sedge weed head on.
Before dealing with what works, let me try to put to bed why RoundUp, which we love by the way as a non-selective weed killer overall, doesn't work. The way RoundUp works is to enter the plant through its flesh, not its root, therefore, while RoundUp might look like it's working, because the part of the weed that you can see dies, the glyphosate in the RoundUp never makes it down to the root of the weed, i.e. the tuber, leaving it there to grow again. Now, if you can get the RoundUp down when the weed is really, really, really young (you can barely see the weed it's so young), then the tuber isn't fully developed and you'll have a better chance.
For best chances of success, you want to use a selective sedge killer that will get into the tuber AND you need to get this stuff down prior that what is called the fifth leaf
development of the weed. It is this stage of development when the weed is still pulling energy from its leaves down into the tuber for growth. After this stage the weed slows down this transfer of nutrition to the tuber and you'll basically get the same result as if you had used RoundUp, i.e. dead above ground, ready to party next year underground.
The best chemical to use is something called halosulfuron, which is sold to the general public as Sedgehammer. The chemical is used in such a minute amount, that Sedehammer is sold in a pre-measured, water soluble bag. Follow all the directions carefully.
You may have heard of something called "Manage". Manage was replaced by Sedgehammer, and Sedgehammer is identical to Manage.
SedgeHammer herbicide is one of a very short list of selective herbicides for postemergence control of sedges, not only for lawns, but ornamental turfgrass, and landscaped areas. Do you have to worry about this stuff getting into your surface or ground water? Can you use it near your well? Sedgehammer has a relatively short half life, with just so so soil binding properties and very low use rates make the chances of this chemical making into your drinking water highly unlikely.
NOTE: Avoid contact of this product to leaves of desirable plants since foliar injury, discoloration or death may result. Safe to use on the following TURFGRASSES When applied as directed under the conditions described, the following established turf grasses are tolerant to this product: Cool-Season Grasses Bentgrass, creeping Agrostis stolonifera Bluegrass, Kentucky Poa pratensis Ryegrass, perennial Lolium perenne Fescue, fine Festuca rubra Fescue, tall Festuca arundinacea Warm-Season Grasses Bahiagrass Paspalum notatum Bermudagrass Cynodon dactylon Centipedegrass Eremochloa ophiuroides Kikuyugrass Pennisetum clandestinum Seashore paspalum Paspalum vaginatum St. Augustinegrass Stenotaphrum secundatum Zoysiagrass Zoysia japonica