Home Pasture Health Forage Tall Fescue: High-Yielding Forage Grass or Toxic and Invasive Weed?

Tall Fescue: High-Yielding Forage Grass or Toxic and Invasive Weed?

Photo From University of Kentucky
Photo From University of Kentucky

During his travels around the state in 1931, Dr. E.N. Fergus of University of Kentucky observed a patch of grass that he thought was worthy of further study.  He collected and increased (i.e., several cycles of planting and harvesting) the seeds, and in 1943 released the tall fescue variety known as Kentucky-31.  Interestingly, this variety now covers the vast majority of the 35 MILLION acres dominated by tall fescue in the United States.  In the ‘fescue belt’ of the U.S., this species is highly productive, persistent, and tends to grow even in places where people do not want it.

What is Tall Fescue?

Like orchardgrass, Kentucky bluegrass, and perennial ryegrass, tall fescue is not native to North or South America.  One source suggests that it is native to parts of Europe, the Mediterranean, North Africa, the Middle East, and Asia, but it has been present in the U.S. for a long time.

Tall fescue is technically a ‘bunch grass’ but unlike orchardgrass and other bunchgrasses it often has short rhizomes (underground stems that travel laterally) and can form a sod.  This characteristic makes tall fescue more tolerant of wheel traffic than most other grasses.  Tall fescue leaves are more rigid than most other forage grasses, have a waxy cuticle on the back of the leaf, and have prominent veins along the length.  Without known exceptions, the leaves feel more coarse than other common forage grasses, a characteristic that often translates to lower palatability.  Modern cultivars branded as ‘soft-leafed’ are likely softer than older tall fescue varieties, but they are still much more coarse than other forage grass species.   Tall fescue grows well in almost all agronomic soil conditions and is more heat- and drought-tolerant than other cool-season forage grasses.

Photo from University of Arkansas

Historically, tall fescue plants have benefitted from a symbiotic association with a fungus (known generally as ‘endophyte’) that grows between the cells in the above-ground plant tissue.   This amazing relationship reduces some types of herbivory, improves drought tolerance and generally bestows better fitness upon plants that are infected compared to those that are not.  Buy why would people not want a high-yielding drought-resistant perennial grass to grow in their  pastures or hayfields?  Unfortunately, the most common endophyte produces alkaloid compounds that are toxic to ruminants and which can result in fever, fat necrosis, tail sloughing, abortion, and even foot sloughing.  Many farmers in the ‘fescue belt’ of the U.S. have learned to live with endophyte infected tall fescue, but it is far from ideal in most situations.

The fescue toxicity problem alone leads to the not-so-uncommon question: WHY WOULD ANYONE IN THEIR RIGHT MIND CONSIDER PLANTING TALL FESCUE??  There are two reasons.  First, there are varieties available that have either no endophyte or an endophyte that does not produce a toxin.  These are the only types of tall fescue that a farmer should even briefly ponder planting if the other plant characteristics fit their forage system.  Second, some of the new endophyte-free and friendly-endophyte varieties are high yielding and have excellent forage quality.  Other important points of discussion include:

  • Forage quality and yield:  As with most forage grasses, the forage quality of tall fescue depends on the harvest schedule.  Tall fescue is later maturing than orchardgrass.  If it is harvested on time, the quality can be very good.  Including red clover in the seeding mixture with tall fescue can improve yields by 30% or more and increase protein levels by 3 – 5%.  Generally speaking the NDF digestibility for modern tall fescue varieties is comparable to orchardgrass.  In most forage variety trials across the country, tall fescue consistently delivers a higher yield than any other perennial forage grass species.
  • Even in many of the endophyte-free varieties, the drought and heat tolerance of tall fescue often allow higher yields to be achieved in sub-optimal conditions.  Neutral detergent fiber digestibility levels also are more consistent among cuttings than with species that are susceptible to drought.
  • Stockpiled fescue for fall grazing. Photo by Garry Lacefield
    Stockpiled fescue for fall grazing. Photo by Garry Lacefield

    Stockpiling potential:  Tall fescue stays green and retains forage quality much later in the season than other forage species.  Stockpiling is the planned accumulation of pasture biomass for fall and winter grazing.  While this could be done in Vermont, the potential for the practice is lower than it is in areas that do not tend to get more than 6” of snow for extended periods of time.

What about invasiveness?

In our never-ending and often misguided pursuit of perfection, we often look for that magical forage variety that will maximize yield and quality while having excellent nutrient efficiency, harvestability, and persistence all while not becoming an invasive weed.  There are too many plant species that were introduced with good intentions but eventually became the bane of land managers; quackgrass, kudzu, johnsongrass, and canarygrass, to name a few.  It is not yet clear whether the non-toxic tall fescue varieties could become invasive in the Northeast as KY-31 has in states like Kentucky, Tennessee, and West Virginia.  Plants without the fungal association are known to be less tolerant of stressful conditions, but the plants are still very competitive and persistent in the conditions of the Northeast.

Organic farmers should be wary of planting tall fescue because it is difficult to eliminate without pesticides.  Tillage practices that are capable of removing tall fescue are expensive, time consuming, and may not be entirely effective.

What about palatability?

Because palatability is the Achilles heel of tall fescue, it is only recommended for use as haylage within dairy forage systems.  While tall fescue can work well in beef and sheep grazing systems, I do not know of any forage specialist (even from the seed companies) that would recommend any variety of tall fescue for a dairygrazing system.  In my work as a student at Michigan State University, I assisted with a study examining the palatability of different grass-legume combinations.  In these small plots there was every imaginable combination of one grass plus one clover species including: orchardgrass, perennial ryegrass, tall fescue, festulolium, red clover, white clover, and kura clover.  When grazed by Holstein steers, heifers, or dry cows, the tall fescue plots consistently received the worst palatability ratings of all the species and often were hardly grazed compared to the plots containing other grass species.  DO NOT PLANT TALL FESCUE IN PASTURES FOR LACTATING DAIRY COWS!  Non-toxic tall fescue can work well in beef and sheep systems, for dry dairy cows, and possibly for dairy heifers, but in these cases tall fescue should be the only forage grass species in the seeding mixture.  Including other forage grasses will likely result in extreme selective grazing and eventual loss of the non-tall fescue grass species.

Orchardgrass is the old standby for many dairy farmers in the Northeast and serves many farmers very well.  This raises an important question:   How does tall fescue compare with orchardgrass?  First, it is important to emphasize that different species of grass require different management for maximum growth.  Crude protein of tall fescue will usually be lower than that of orchardgrass harvested at the same stage of development, fiber levels are similar, but the NDF digestibility of tall fescue tends to be higher than that of orchardgrass.  The following forage quality data is from a demonstration conducted in North Danville, VT:

Forage quality of tall fescue without legume component












































Forage quality of tall fescue with red clover component











































Forage quality of orchardgrass with legume component







































Fungal endophyte among tall fescue cells. Photo from Virginia Tech
Fungal endophyte among tall fescue cells. Photo from Virginia Tech

Could Endophyte free tall fescue become infected over time?

The toxin-producing fungal endophyte that characterizes Kentucky-31 and other older tall fescue varieties is passed through the seed.  The seed becomes infected while it is still attached to the parent plant.  There is no known mechanism for an endophyte-free plant becoming infected.  This raises the obvious question about how tall fescue became infected in the first place! Nobody seems to have a ready answer for that question, and it is possible that the original infection(s) happened thousands of years ago under very unusual circumstances.   That being the case, the literature is in agreement that the only way for an endophyte-free stand coming to have endophyte-containing fescue is through the introduction of endophyte-infected seed.


  • If you plant tall fescue, always select endophyte-free or ‘friendly endophyte’ varieties.  There is no known mechanism for the plants established in these systems to become infected with the toxic endophyte.
  • When planted in with red clover in haylage systems, these tall fescue varieties are can give high yields of dairy-quality feed.
  • Tall fescue can be difficult to eliminate without herbicides, so it is not recommended for organic systems unless the producer knows that they want to grow tall fescue on their fields indefinitely.
  • Tall fescue should not be planted in grazing dairy systems.  In beef, dry cow, heifer, and sheep pastures, do not plant tall fescue with other forage grasses


  1. Great article! As a Virginian, fescue is definitely the king of grass where I’m from. But recently there’s been some great research about how converting some pasture to native warm-season grasses in the fescue belt can mitigate the summer slump a great deal. They had a cost of just 31 cents per pound of gain per acre, which was including the cost of establishment.


    It’s better for wildlife, water quality, and drought mitigation too.

    My ideal setup in Virginia would be 1/3 NWSG, 1/3 introduced cool season grasses (VA used to be the orchardgrass capital of the nation), and 1/3 fescue for winter stockpiling.

    • Shayan,

      Very interesting idea. My graduate research at Michigan State University looked at a system similar to what you are describing I will try to turn that into an article in the near future. Briefly, I will say that big bluestem was far more palatable than switchgrass. Gains were not affected as long as they were not on the NWSG too long before rotating back to cool-season grasses. Establishment for switchgrass is particularly slow, which is costly. Also, grazing starts about a 4-5 weeks later in the spring and ends a month before the end of the cool-season grass grazing season. Warm-season grasses are slower to start in the spring and need to ‘refill’ their root reserves prior to the winter.

      For a producer trying to maximize profit/acre, this was not a great system for Michigan, but it might work well other places. For producers who have great concern about wildlife but are less concerned about profit/acre, it might be helpful. While it is very palatable in the summer, big bluestem goes flat during the winter, while switchgrass stands up nicely. Deer did seem to appreciate the cover that the switchgrass offered in the winter. I am not sure how beneficial the NWSG would be to nesting birds if the producer’s goal was to maximize livestock gain on that grass. The animals would need to be going into those pastures before most of the young birds have fledged. At traditional stocking densities, things probably would not go very well for the nests.

      • Thanks for your response and sharing your study results!

        I think there’s definitely a regional component–in the UTK studies, the daily gains weren’t bad at all, with much of the ADG values approaching those of corn silage. Pretty amazing, considering the bad rap NWSG get.

        In Virginia in the summer, when the fescue’s all crispy, I regularly see the NWSG pastures boasting stands exceeding 5 or 6 feet tall, with the densest growth around 3 feet. The productivity per acre has to be huge, and Patrick Keyser of UTK has said that the traditional measures of forage nutrition did no justice to the gains they saw.


        They started grazing after giving the grass just one year to establish, and it didn’t seem to impact it much.

        All in all, I’ve been pretty impressed with the stuff coming out of UTK, and when I’m more permanently situated, I’d like to try it for myself.

        Thanks again for a great article and your comments!

  2. Dan,

    You mentioned Kentucky Bluegrass is not native to N.A. Are we sure about this. There are references that suggest KBG is native to the northern regions of NA.

    As a grassland ecologist, I have a hard time considering we didn’t have a strong Poa component in our grasslands.

    • Hi Steve,

      Thanks for the comment. Discussions about native vs. non-native are intriguing for a number of reasons.

      I think that there are several ways to answer the ‘native’ question. The first is ‘ask the government!’ The USDA classifies Kentucky bluegrass (poa pratensis) as ‘native and introduced’: ” Native and Introduced – some infra-taxa are native and others are introduced.”

      This means that there they think that there were representatives of the poa genus here prior to European settlement. Among many other reputable sources, there seems to be little dispute that what we call ‘Kentucky bluegrass’ was brought here by Eurpoean settlers. It is worth noting that some members of the festuca (fescue) genus are native to North America.

      I agree that it is possible (even likely) that there is some genetic influence of our native poa species in Kentucky bluegrass. I would be interested to learn more about how similar KBG is to the representatives of the poa genus that may have been here prior to European settlers.

      I am not sure how useful this analogy is: Bison are native to North America, but we brought the bos tarsus and bos indicus types of cattle. They are native in the sense that there were ‘cattle’ here previously with bison can potentially reproduce. From an ecological perspective, they are different in many ways.

  3. Our farm in southeast PA is within the “fescue belt” and our pastures have been well endowed for years with Endophyte toxic Tall Fescue (E+TF). Killing it out and replanting with a less toxic cultivar or other forage is not a risk that I would take. We consulted with Jim Gerrish some years ago, and he suggested a breeding program intended to give us a breeding herd that would become adapted (tolerant, resistant) to this otherwise excellent forage. It has taken some years, but I’m pretty sure we’re there now (fingers XX’d). Our grazing program takes strategies from Greg Judy, including NO mowing to reduce seedheads, a tactic recommended by many to reduce fescue toxicity. Seed-heads of E+TF are rich in the ergot alkaloids (EA), toxins produced by the endophyte which mediate the toxic effects of this forage. Needless to say, I was very nervous at first about giving up the mowing option, but so far this has resulted only in huge savings of my time and money, albeit with continuing “summer slump” among juniors in the herd .
    We have been sending forage and urine samples to measure content of EA (Agrinostics Ltd, Watkinsville, GA) in order to get quantitative estimate of the toxic load ingested by our cattle from time to time over several years**. To make a long story short, we frequently find urinary EA titers elevated 10-100 fold in breeding females that go on to conceive and deliver normal calf. This finding was unexpected because titer of urinary EA is inversely correlated with weight gain in stockers grazing E+TF and has thus been proposed as objective marker for fescue toxicity **. The whole story is complex, and I’m still working on it (6 yrs!), but my best guess to account for the high titers of EA in good-doing breeding cows is the same as set forth in my comment posted above re Kathy’s Hemlock eaters (see June3, Poisonous Plants…)
    **N.S. Hill et al- 2000. Urinary alkaloid excretion as a diagnostic tool for fescue toxicosis in cattle. J.Vet.Diagn.Invest 12:210

  4. “Including other forage grasses will likely result in extreme selective grazing and eventual loss of the non-tall fescue grass species.”

    Stand diversity is really an issue of management. Graze tall and let the plants recover between grazings. I don’t mind that my cows avoid the fescue in the summer. They eat the wild oat, bluegrass, smooth bromegrass, rye, orchardgrass, foxtail, dandelion, chickory, narrow-leaf plantain, plantain, the full spectrum of clover, lambsquarters, horseweed, ragweed and sometimes the thistle. They trample everything uneaten to the ground. The cows get plenty to eat. The soil, thanks largely to fescue and high cattle density, gets plenty to eat. After 50 years of continuous grazing, the change of management is causing the pastures to thicken and increase in diversity.

    A fair portion of the fescue gets eaten in the summer and there is no doubt that the fescue is infected. Some cows do better than others infected fescue, just as some cows do better than others on corn. Rather than rip, spray and seed the world with “improved” varieties, the solution is to select for cows that breed back every year on your native forages and manage your pastures for diversity. If all else fails, broadcast 5# of red clover every year until the stand gets established. It worked for Greg Judy.

    Haylage? How would you pay for it?

    • Chris,

      Thanks for the comments and questions. The recommendation to use improved varieties is primarily in the context farm managers who have already made the decision to seed down a new pasture or hay field and is making decisions about what seed mix to use. In this case, the field might be coming out of corn silage production, or it could be recently cleared land. The comments are especially directed toward producers living in areas where tall fescue has not traditionally been used and where cows have not been selected for their compatibility with endophyte-infected tall fescue. This is the situation in the Northeast.

      You are right that the botanical composition of the pasture reflects the management history of the field. Hungry cows will eat fescue. In my experience, however, they will eat everything else first, and often eat it to the ground, which reduces the chances of survival of that plant and improves the odds for the fescue. I do not encourage graziers to plant mixed stands that include tall fescue because they will not end up with the botanical composition that they might expect based on the seed tag. Under most management, tall fescue will dominate, other pasture species will be grazed into oblivion. Other species that they may or may not prefer will fill in the gaps.

      In a mob-grazing situation, the outcome might be different — I cannot say for sure. Unlike some, I think mob-grazing is best used as a tool to complement to other time-tested grazing practices — not as the centerpiece of a grazing management system. For example, when I first turn the livestock out in the spring, I want them to eat the tops off of just about everything; a very low stocking density will accomplish this goal. As I am trying to keep up with the pasture at the stage that seedheads are being produced, mob-grazing becomes a very attractive practice.

      As a livestock producer, if I had a choice for my livestock to eat non-toxic fescue or to avoid toxic fescue in the summer, I rather that they eat the non-toxic fescue. A few reasons include: more grazing days per acre, higher weight gains per acre, less grazing time, improved forage utilization — all factors that influence economic sustainability.

      That said, I agree with what you say about using the animals that work given your situation. If endophyte-infected tall fescue is endemic in your area, it will pay to have cows that tolerate it.

      Finally, regarding haylage: almost all dairy farmers in the Northeast harvest at least some of their forages as haylage. The exception would be some cheesemakers and a few ‘very traditional’ producers. One of the ways it pays for itself in this part of the world is that it allows farmers to harvest the crop earlier in the spring and get the crop into storage before it gets rained on. Intense forage managers organize their workflow to allow them to mow in the morning and start putting it into the bunker silo in the afternoon of the same day. The feed quality in this system is outstanding.

      • That was an excellent response.

        Where I am I would have to kill the infected fescue in the ditches – even on the neighbor’s side of the road – to get ahead of it. It always comes back.

        I still can’t imagine haylage…but I don’t live in the Northeast. Interesting about morning mowing as the brix would be lower.

  5. Hi Dan–interesting article giving the history of Ky31.

    While dairy graziers in the Northeast may not want to plant novel endophyte fescue for their lactating cows many dairy graziers in Southwest Missouri [a hot bed of grazing dairies] are finding it a good alternative to ryegrass and orchardgrass, two grasses often unable to tolerate the heat and dry spells of summer. Here is a link to the Southwest Missouri Research Center Dairy, a working grass based dairy run by University personel. http://aes.missouri.edu/swcenter/grzdairy.stm

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