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2012-05-03

King Ranch Bluestem - weed or forage?

By Judith Pannebaker BCC Editor

Those desiring the definitive treatise on King Ranch bluestem - aka as KR Bluestem and, more formally, Bothriochloa ischaemum var. songarica (whew, what a mouthful!) - should refer to the online article, "Three Decades with KR Bluestem," available at
http://www.biosci.utexas.edu/prc/DigFlora/KR/KR.html. The rest of you are advised to just read on, MacDuffs.

Online websites seem to be evenly divided between considering the grass a fair-to-middling graze for livestock and seeing it as a noxious weed to be destroyed at all costs.

However, everyone agrees this perennial bluestem is not native to Texas. In fact, legend has it the original King Ranch bluestem seed was collected near Amoy, China in 1917.

The current incarnation traces it roots - pun intended - back to plants found growing on the King Ranch in 1937.

A warm-season grass persistent in South Texas, KR bluestem can withstand winter temperatures as far north as central Oklahoma.

Growing from 18 to 48 inches tall, the pseudo-bunchgrass has light green stems that branch freely, and turn a straw color when mature. This tendency contributes to the grass' other common name, Texas yellow beard grass.

The leaves of KR bluestem are thicker near the collar with the upper surface covered with small hairs. Its flower clusters appear as spikelets, which bloom from June through October.

KR bluestem has adapted to a well-drained shallow sandy soils, loams and clays. Although drought resistant, it cannot tolerate flooding.

Apparently, the agricultural industry developed cultivars of KR bluestem to improve degraded rangelands. A cultivar is a plant or group of plants selected for desirable characteristics that can be maintained by propagation.

When used as permanent pasture, KR bluestem can produce good hay, providing fair grazing for cattle and sheep. It can be grazed throughout the winter.

The grass has also been used for soil conservation and for reseeding eroded soils. Because of its extensive root system, KR bluestem can be an excellent ground cover - even on infertile soils.

However, according to one source, widespread planting by ranchers and by Texas Department of Transportation personnel led to a serious ecological threat on roadsides where the grass was used to control erosion.

In her 2008 article, "Where Did All the Bluebonnets Go? Somebody Messed With Texas Wildflowers!" - available online at http://www.trinity.edu/departments/public_relations/trinity_people/kelly_lyons.htm - author Susie P. Gonzalez postulated that the evil effects of the controversial grass began 20 - well, now 24 - years ago.

Back then, TxDOT began seeding roadways "with a weed known as King Ranch Bluestem" to prevent erosion and stabilize soils. However, the non-native grass ultimately contributed to the disappearance of springtime displays of bluebonnets and other native wildflowers.

In fact, in 2007, the Texas Invasive Plant Conference devoted an entire day's symposium to the eradication of KR bluestem.

Timely mowing, burning and herbicide application all suppress the grass.

While mowing will not rid KR bluestem completely, it will, of course, curb the spread if completed before the grass flowers and turns to seed.

(Sources: texasinvasives.org/plant_database, www.biosci.utexas.edu, www.ars-grin.gov/, www.wildflower.org/
www.curtisseed.com, www.tropicalforages.info and
www.bes-tex.com/page_print.php?kei=46)


Photos by Lynn Post