Tall Fescue

Identifying Characteristics:

• Bunch-type cool-season grass
• Membranous ligule
• Young seedhead appears to be spikelike, but it is a panicle
• Distinct veins on leaf blade
• No obvious midrib on upper leaf surface
• Thick leaf blade as compared to most grasses
• Extremely small serrations on leaf blade edge cause a rough feel

Plant Longevity:

• Perennial

Where Commonly Found:

• Pastures
• Hay fields
• Roadsides
• Waste areas

Time of Most Concern:

• Late spring and summer months, especially in pure stands and when receiving high rates of nitrogen

Compound that Causes Concern:

• Ergovaline alkaloids produced by an endophytic (within plant) fungus (Acremonium coenophialium) are primary responsible for toxicity syndromes
• Alkaloids cause constricted blood flow that limits ability to regulate body temperature

Part of Plant Most Toxic:

• Seed, stem, and leaf sheath

Livestock Species Affected:

• Horses and other equine
• Cattle
• Sheep, to a lesser degree

Pasture, Stored Feed, Both:

• Both

Clinical Signs:

• Lameness (fescue foot)
• Fever
• Non-shedding hair coat
• Decreased weight gain
• Reduced conception
• Reduced milk production
• Longer gestation time with equine
• Standing in water because of fever
• Rapid breathing
• Heat and cold stress

Amount Needed to be Consumed for Clinical Signs / Death:

• Dependent on concentration of ergovaline alkaloids
• Important Note:
  • Low-endophyte and novel (friendly) endophyte varieties are not a fescue toxicosis risk
  • Concentration of ergovaline alkaloids varies throughout the year; greater concern when seedheads are consumed and lesser concern when stockpiled
  • Inclusion of red clover, reduces blood vessel constriction