Published on 05/22/13

Spring conditions ideal for deadly fungus in forage fescue

By Frank M. Watson

Cattle producers should watch their herds for signs of fescue toxicosis this summer. Conditions this spring are ideal for the deadly fungus that attacks tall fescue, but good forage management can help prevent problems with toxicosis.

Cooler than normal spring temperatures and above normal rainfall combined with adequate fertilization causes conservatively stocked fescue pastures to grow more grass than cattle can eat. Most tall fescue in north Georgia is now infected with the fungus that produces livestock toxins called ergot alkaloids.

This fungus (endophyte) lives within tall fescue, improving its drought tolerance and stand persistence on poor soils. Managed appropriately, the buildup of toxins in fescue can be kept to an acceptable level.

Ergot alkaloids are at their highest levels when plants get tall and lush. Tests have shown levels in seed heads are five times higher than in other plant parts. Cattle grazing fields that are candidates for commercial seed production are most at risk. Those herds are more apt to eat the infected seed heads when they are fresh and succulent from adequate rainfall.

Make adjustments to lower risks

Management for preventing toxin buildup includes adjusting the stocking rate to keep grass at the proper height and preventing massive seed head production. Cattle producers can also reduce fertilization if necessary to slow rapid growth. If the grass gets ahead of you, get out the bush hog and cut it back. At the very least, clip off the seed heads. Adding clover to the pasture will help to dilute the toxins. Clover can sometimes be planted with a notill drill.

Fescue toxicosis can reduce cattle performance even before many of the noticeable symptoms show up. Consumption of toxic endophyte-infected tall fescue depresses body condition. It reduces milk production in cows and weaning weight in calves. Collectively, these problems are called fescue toxicosis.

Grazing toxic tall fescue pastures or consuming toxic tall fescue hay decreases cattle’s forage intake, lowers average daily gain and alters hormone concentrations in cattle and other livestock.

Rough coats, heat stress are symptoms

As conditions worsen, cattle begin to exhibit visual symptoms, the most common being rough hair coats and heat stress. Infected cattle typically wade in ponds or lay around in the shade when they would typically be grazing. In extreme cases, they may lose ear tips or tail switches.

While mineral supplements won’t counteract the toxins, supplemented cattle can tolerate the toxins better. Using good quality minerals always yields return on investment, but even more so under conditions of potential fescue toxicosis.

For more information, search “fescue toxicosis” on the University of Georgia College of Agricultural and Environmental Sciences publication website at

Frank Watson is the University of Georgia Extension agent in Wilkes County, Ga.

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