Toxic tall fescue has been around so long many producers no longer recognize its devastation, says Craig Roberts, a University of Missouri extension forage specialist.

“It's like carrying a backpack all your life; you don't know how heavy it is until you take it off,” he says.

Toxic tall fescue, grown on well over 40 million pasture and hay acres in the U.S., causes one of the most costly animal disorders facing livestock producers in eastern states. It negates weight gains and hurts milk production and reproduction in cattle, horses and sheep.

Roberts and Richard Crawford, a Missouri animal scientist, are determined to change that. Their two-day Tall Fescue Toxicosis and Management Workshop combines 10 demonstrations and several discussions to show how to manage the crop to reduce its toxicity.

“In Missouri, we're looking at about 85-90% of our fields as highly toxic and 1% not very toxic. The tall fescue Kentucky 31 was planted with the toxic endophyte growing in it. It's part of the seed, so it was disseminated across the fescue belt,” Roberts says.

The fescue belt runs from Tennessee, Kentucky, Missouri and the southern parts of Indiana and Illinois east through the Mid-Atlantic states. “In a lot of these regions, especially where there is shallow soil, there isn't much that will grow year-round. Our producers have tried orchardgrass and bromegrass, but only tall fescue seems to persist. It withstands diseases, grazing pressure, drought and living organisms.”

Although there are endophypte-free fescues, as well as novel-endophyte, less-toxic varieties, growers are slow to replace Kentucky 31, Roberts says. So, as part of the workshop, side-by-side comparisons are made of cattle fed toxic fescue vs. non-toxic. In the first session, participants had only to walk off the bus to see what toxicity does to cattle.

“When we walked up to them, heifers on endophyte-free fescue wandered around and were a little shy. In the next pen, the heifers on the novel endophytes also behaved normally. Heifers in the toxic fields ran to the far back corner, stuck their heads in the corner and started urinating. Excessive urination is one of the symptoms,” Roberts says.

The workshop also demonstrates what management practices will prevent or reduce toxicity. “Nearly all of the practices we recommend, they're doing anyway. But I think the timing is off. If you move steers to alfalfa, bermudagrass or some other summer pastures, they should be moved sometimes two weeks earlier than when our producers are moving them. They're moving cattle based on yields or forage availability. They should be moving them based on toxin levels in the fields,” Roberts says.

If replacing toxic fescue isn't feasible, consider these other management practices, which can reduce toxicity:

  • Diluting tall fescue in pasture by interseeding legumes and other grasses. Red and white clover, according to university studies, can allow a steer to gain an extra 0.20 lb/day during spring/summer grazing. Non-toxic fescue is another interseeding option in some situations.

  • Providing supplements. Feeding grains, oilseeds or grain milling byproducts, as well as silage and non-toxic hay, can decrease forage intake and dilute tall fescue toxins in the diet.

  • Fertilizing pastures with low rates of nitrogen. Higher N rates rapidly increase alkaloid concentrations. Alkaloids, produced by the endophyte fungus, cause toxicosis.

  • Ammoniating toxic tall fescue hay. Treating low-quality hay with anhydrous ammonia not only makes the hay more digestible, it also detoxifies the hay to some extent.

  • Managing winter grazing. Instead of grazing stockpiled tall fescue pasture early in winter, switch to hay. Stockpiles grazed later have reduced amounts of alkaloids.

  • Controlling seed heads in the field. Clipping seed heads not only maintains forage quality, it also reduces alkaloid concentrations in the pasture.

The next fescue workshop is Oct. 4-5 at the Southwest Research Center, Mt. Vernon, MO. For more information, call 417-466-2148, email or visit for a registration form.