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Sneaky Pasture Weeds – Sedges and Rushes

By   /  July 21, 2014  /  3 Comments

Do you have these? Here’s how to tell!

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We’ve discussed pasture grasses, legumes, pasture weeds and management ideas for pasture improvement on these pages many times before.  All good topics.  When you call to mind pasture weeds though, I’d bet you picture milkweed, goldenrod, a couple different types of thistles and maybe bedstraw.  These are pesky and important weeds in many pastures, but there are other, sneakier weeds that may escape your attention.  These sly and mischievous weeds require closer inspection and a bit more scrutiny to figure out.

A well-managed northern New York pasture.  Photo by Kitty O'Neil.

A well-managed northern New York pasture. Photo by Kitty O’Neil.

Ideally, pastures are dense, perennial sods consisting of mixtures of high-yielding, palatable grasses and legumes.  In reality, most pastures do not quite match this perfect ideal.  Weeds are normally present in some number, ranging from insignificant to seriously problematic, depending on management and history.  Weed density within a pasture can change over time, and can vary from one area to another within a pasture.  You may notice, in your own pastures or hay fields, that weeds are often not distributed uniformly, but rather that some plant species are concentrated on knolls, along the woods, in wet spots, or in high traffic areas.

Let’s turn our attention to some particularly sneaky weeds that are often, but not always, found in lower, wetter areas of the pasture – the sedges and rushes.  I’m referring to them as ‘sneaky’ because they’re a bit harder to spot in the pasture.  They look a lot like grasses to an amateur observer, but that is about as far as the similarities extend.  As a group, grasses consist of a jointed stem with a few tillers, long and slender leaves with parallel veins.  They range in height from turf to giant bamboo.  Grasses may be annual or perennial but all have their growing points near the soil surface, so they can survive repeated mowing or grazing.  Grasses reproduce via seed or underground structures.  Most of the hay and pasture grass species (bluegrass, orchardgrass, timothy, fescues, reed canarygrass, etc.) are quite palatable and produce moderate to high yields.

Sedges have edges as seen in this magnified view.

Sedges have edges as seen in this magnified view. Photo courtesy of hiltonpond.org

Sedge and rush species also have long slender leaves but occupy completely different branches on the evolutionary tree of life than grasses.  Sedges and rushes are perennials that livestock typically avoid, finding them unpalatable.  There are well over 1000 different sedge species, but the most common sedge found in Northeast pastures and hayfields is Yellow Nutsedge.  Yellow nutsedge is noticeable for its pale green color, spiky flowers and underground tubers, but its most distinctive feature is its stem.  If you compare the lower stems of sedges and grasses, you’ll discover that sedges typically have triangular stems without nodes while grasses have round or flattened stems with nodes.  This key difference is the reason for the memorable phrase “sedges have edges, but grasses have knees.”  Sedges reproduce by underground tubers and rhizomes.

A magnified view of the round Rush

A magnified view of the round Rush. Photo courtesy of hiltonpond.org

Rushes are short plants that resemble grasses and sedges and are also found in lower, wetter areas of a pasture or hayfield, although rushes may grow in drier or compacted areas too.  The unique feature of rushes is their 3-petal, lily-like flowers.  In fact, botanists refer to rushes as “lilies turned to grass” to help them remember their distinctive flowers.  Rushes reproduce by vegetative rhizomes or by seed.  The tough, wiry, round stems of rushes are also avoided by livestock who generally do not find them palatable.  In the Northeast, the most common of the rushes is Slender Rush.

A hollow grass stem.

A hollow grass stem. Photo courtesy of hiltonpond.org

Nutsedge and rushes might be most noticeable as animals are finished with a pasture or paddock.  The livestock will have eaten grasses and other appealing plants, leaving behind patches of Yellow Nutsedge and Slender Rush.  It is disappointing to see large, uneaten areas of low-yielding, unpalatable pasture, but biological features of rush and sedge make them difficult to control.  Their underground reproductive structures make mowing or clipping ineffective as a means for removal, but this strategy can slow their spread, if it is timed before flowering.

Photo courtesy of www.agry.purdue.edu

Photo courtesy of www.agry.purdue.edu

Herbicide options for these two weeds are limited, but Permit and Yukon have recently had hay and pasture applications added to their labels.  They may be used on yellow nutsedge in grass pastures with no grazing restriction for lactating or non-lactating animals.  If the field is not too wet for machinery, suitable grasses or legumes can be overseeded with a no-till drill or, as a more drastic measure, the sod may be killed and soil can be tilled for replanting of appropriate grasses and legumes.  Often though, the sedges and rushes occupy areas that may be difficult to access with tractor equipment.  In this case, the field could be tiled for better drainage if that option is economically advantageous.  Legume species such as red or white clover can be frost-seeded in the spring to try and introduce more desirable species, but the rush and sedge species will likely persist.  Sedge and rush weeds take a keen eye to notice, but their impact can be just as important as thistles or milkweed or goldenrod in a pasture or hayfield.  Their presence reduces overall productivity of the field and presents a challenge to the farm manager.

Additional resources:

Uva, Neal and DiTomaso, Weeds of the Northeast, Ithaca, NY: Cornell University Press, 1997.

 

For more information about field crop and soil management, contact your local Extension office or Kitty O’Neil, Regional Field Crops and Soils Specialist, Cornell University Cooperative Extension, 315-379- 9192 x253;

 

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3 Comments

  1. Steve Nelle says:

    Some sedges and rushes are unpalatable while others are very palatable (just like grasses). True sedges (Carex) are often very palatable, productive and nutrititious forages and they often occur along creeks and river bottom areas or around the perimeter of ponds. Also, it is common for true sedges to green up much earlier than grasses and stay green after frost.

    Within this large generic group of sedes and rushes includes many plants that the astute manager / grazier should become familiar with. These include: spikerush, bulrush, flat sedge, true sedge, true rush, and many others. In some cases, riparian or wetland pastures may require special management in order to get best use of these.

  2. So are these weeds cows can learn to eat? I saw my cows eating yellow nutsedge one wet spring when it was the first thing to emerge in that pasture. Do we know anything about the nutritional value and/or toxicity of reeds and nutsedge?
    Thanks.

    • Kathy Voth says:

      The biggest problem with these plants is that they are often not very high in nutritional value. Animals can learn to eat them, though I would probably teach them to eat something else first that is higher in value. My experience is that once animals have started experimenting with foods, they will readily add a bit of everything in the pasture, even things low in nutritional value.

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