Grazing Oklahoma: Old World Bluestems

(Photo courtesy of the Noble Research Institute)

By: Rob Cook, Noble Research Institute pasture and range consultant/rdcook@noble.org

Characteristics: Old world bluestems are introduced, warm-season, perennial bunch grasses. Mature height is about two to four feet tall. The leaves are up to 3/16-inch wide and four to eight inches long.

The leaves are linear and have hairs on the surface that get thicker towards the stem. The stems are often yellowish in color. The seed head can contain two to eight branches and can sometimes be confused with native bluestem varieties such as silver bluestem and big bluestem.

Area of Importance: Old world bluestems are now a common grass, growing on various soil types across the plains of Oklahoma and Texas, but it is typically planted on heavier textured soils. It has an ability to establish and flourish in bare soils.

For this reason, it was commonly planted in monocultures in Conservation Reserve Program (CRP) plantings, and to stabilize soil along roadsides and right-of-ways. Old world bluestem is a name given to a group of several different bluestem varieties. There are two different species that make up the group. Bothriochloa ischaemum are the yellow bluestems that include varieties commonly known as Plains bluestem and King Ranch bluestem. Bothriochloa bladhii are the bluestems that include varieties commonly known as Caucasian bluestem and WW B-Dahl bluestem.

It provides fair to good grazing for livestock. Old world bluestems provide poor forage values for wildlife, and the seeds are not used by grassland birds.

Attributes: Old world bluestems have escaped from the areas originally planted in and invaded into native rangeland across the Southern Great Plains. It is commonly seen in pastures, fields, ditches, roadsides, pipelines, and even yards across Texas and Oklahoma. It is so well adapted to establishing from seed that it is seen as a weedy grass at best and an invasive species by many land and wildlife managers.

Some studies have shown that Old world bluestems are able to change a soil’s chemical composition, reduce seed germination and slow the growth of other plants around it. Many varieties are considered increasers under continuous grazing because the plant is able to tolerate grazing better than many native forage species. When heavily grazed, Old world bluestem will take on a decumbent growth form where the leaves will grow close to the ground and spread out from a flattened base before the stems bend up to raise the seed head. This makes the leaves difficult for cattle to graze.

Varieties such as Plains and WW-B.Dahl have high production potential when managed correctly. The production potential and relative ease of establishment on even degraded soils make these grasses a popular choice to plant for establishing grazing or hay lands. However, other species of introduced or native forages should be considered and the planting of Old world bluestems should be discouraged because of its ability to invade even properly managed native rangelands. These grasses are present in widespread areas, and chances are many pastures have them in some density.

Control with herbicides and fire have been shown to be greatly ineffective. When it is present, grazing and wildlife managers often have to manage what they have. Proper grazing utilization of the native plants will allow them to compete with Old world bluestems and serve as the best management technique to slow its invasion.

References:

Coffey, C.R., R.L. Stevens. Grasses of the Great Plains: A Pictorial Guide

Linex, R.J., 2014. Range Plants of North Central Texas