Try Sedgehammer

Nutsedge produces a bulb like underground structure and grow by rhizomes thus making them very difficult to eradicate. Repeated application of the two herbicides you have used will work over time. Be very patient as it takes weeks for the effects of the herbicide to show sign of its effects. The labels should state the repeat application intervals.

Understanding how and where sedgfes grow is part of eliminating them from where you do not want them. Short of spending a lot of you money on those two products the best means of control is to look closely at the soil to see why that sedge is growing there and sedges grow in soils that are moister, wetter, than normal. Sedges are bog plants and like warm, moist soils.

Here is a link that might be useful: Yellow Nutsedge

Thanks for the suggestions and the link. I guess persistence is the key.

I'm guessing that kimmsr doesn't know the real habits of the nut sedges very well. Once introduced into an area, they can and do thrive under all kinds of conditions and in all kinds of soil types. Yellow and/or purple nutsedges can take over a sandy, arid site, a well-drained clayey location, and everything in between.

Thelma, we have the darned stuff trying to take over a couple of our beds, too. I've found that keeping it pulled while it is still young is very helpful. Attempting to dig it out might simply serve to propagate it. My husband will treat emerging plants with Image and it works very well.

rhizo, I know more about how the sedges grow as well as where they prefer to grow than most people excpet those that spend their lives studying sedges do. Most often I find that people think they know and will not take the time to learn and therefore have false notions. I have had people tell me, "I know how sedges grow and your "experts" are just plain wrong." and these people refuse to look at what someone with a pHD in Botany, Soil Science, Horticulture, or other similar fields will tell them because that might well cause them to have to change their knowledge base.
Sedges are plants of bogs, wet soils, that is where they grow. That is where I have seen sedges grow all my life and where I still see them grow today. In yards and gardens when I look closely I find the soil is wet, providing the environment sedges like to grow in while the property owner tells me that the soil where the sedges are growing is dry, and then I find that that person simply assumed the conditions were what they thought they were and they never really looked.

Again, I find your interpretation a narrow one.

Sedges are, indeed, happiest in moist locations. However, 'real life' situations place them in a wide variety of soil conditions where they are able to thrive, if not controlled.

It's important to marry technical knowledge with personal observation and experience. Together, they make a formidable partnership. Alone, not so much.

i am going to jump in here. i live in san diego and been fighting nutsedge since i bought my house four years ago. i think it came in thru the prior owners planting of sod.

anyhjow i have heard the argument that it is more of a soil issue than a weed issue. i gotta disagree after seeing how pervasive and incredibly difficult it is to control and kill nutsedge.

compacted soil, wet soil, dry soil, whatever, once you have it you have a battle on your hands. what the hell are you supposed to do if you have "compacted" or wet soil? dig 2 feet down and replace it? let it dry out so the grass dies? nutgrass will thrive when it is not watered way more than fescue once established.

all this history and botany of nutgrass is interesting b ut if you want to kill it spend the money and buy sedgehammer. i spent $140 on ebay last summer and worth EVERY penny.