Remove cool-season grass seed heads before they emerge

WEST PLAINS, Mo. – “Missouri livestock producers have some options to manage tall fescue seed head development and the toxic endophyte issues we have in Missouri,” says Tim Schnakenberg, University of Missouri Extension field specialist in agronomy.

Seed heads emerge in tall fescue grass pastures by mid-May across most of Missouri.

Sarah Kenyon, MU Extension field specialist in agronomy, says it is important to know how forage grows to understand the effect seed heads have on quality.

When seed heads form, plants move resources away from making leafy forage and focus on reproduction. Leaf growth slows and eventually stops as plants use proteins and sugars to make seeds instead of leaves. This results in a more fibrous plant with lower forage quality. Plants can be encouraged to stay in a vegetative stage by mowing or grazing to prevent seed heads from developing.

There are several ways to remove seed heads: hay production, early grazing, clipping or chemical suppression of tall fescue.

Baling hay before seed heads form allows the plant to resume leaf growth, says Kenyon.

Another option is to clip or “reset” paddocks by removing the seed head. Once the seed is removed, the grass remains vegetative longer. This extends the growing season and results in higher-quality pastures and hayfields.

Grazing discourages forage tillers from making seed heads. For better grass quality and quantity, nip the seed head tiller.

MU Extension agronomist Jamie Gundel recommends that producers move livestock every day or two to small pasture paddocks as part of a management-intensive grazing system.

Seed heads of Kentucky 31 tall fescue present special risks when fed to cattle. As seed heads emerge, toxic alkaloids concentrate in the seed. K-31 is the most widely used grass in Missouri pastures.

Fescue toxicosis costs Missouri’s beef industry $160 million each year in reduced weaning weights, conception rates and milk production. Cattle run high internal body temperatures and respiration rates and experience reduced blood flow, which can cause lameness and loss of hooves.

“There is no single management practice to reduce the impact of fescue toxicosis on livestock,” says Gundel. “Therefore, producers should use incremental alleviation, the additive effect of multiple management strategies.”

This involves interseeding legumes and other forages, clipping seed heads, rotating livestock to warm-season paddocks, grazing height management, nitrogen management or applying herbicides with the active ingredient metsulfuron at least three weeks before emergence to suppress seed heads.

Another option is to renovate K-31 pastures to novel-endophyte fescue, says Kenyon. Novel endophytes offer the same benefits as the endophyte in K-31 tall fescue but without toxicity issues. They also provide better stand persistence than endophyte-free varieties.

To find out more about managing tall fescue, contact an MU field specialist in agronomy. In southern Missouri, they are Tim Schnakenberg at SchnakenbergC@missouri.edu, 417-357-6812; Jamie Gundel at GundelJ@missouri.edu, 417-778-7490; and Sarah Kenyon at KenyonS@missouri.edu, 417-256-2391.

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University of Missouri Extension