“It is akin to a viral pandemic, swallowing up chunks of what few can accurately describe with words, few thoroughly understand, but what used to be waves of bluebonnets and paintbrushes in the spring, crimson stands of native prairie grasses in the fall, and carpets of yellow flowers interspersed by funny looking grasses whose seeds stick in socks and shoestrings. The native Texas landscape is disappearing before our eyes, under a sea of the wrong grasses.”
– Forrest Smith, Texas Today: A Sea of the Wrong Grasses
Blame it on the rain or the people who first brought King Ranch (KR) bluestem to Texas almost a century ago, but this ubiquitous, non-native grass is looking particularly lush and abundant in Texas this year. Drive down virtually any rural Texas road and you’ll see KR bluestem, often dominating open spaces. Why is this invasive grass that originated in China here, how can we control it, and why do Texas landowners hate it so much?
King Ranch bluestem history
KR bluestem, along with its invasive cousin Kleberg bluestem, was not always so despised. Indeed, at one time they were both haled as ranch saviors in the wake of the Dust Bowl when pastures were decimated by drought and overgrazing. Originating in China, KR bluestem made its first stop in the U.S. in California in 1917 before being introduced in Texas in 1924. As described in “Introduced Bluestem Grasses: Management on Native Lands,“ in 1939, the Texas Agricultural Research Service named the plant yellow beardgrass and released the seed for commercial production in 1949.” Kleberg bluestem, which can be difficult to distinguish from KR bluestem, but it does tend to be a little taller, originated in South Africa. It was found growing with KR bluestem in 1939 on the King Ranch. In 1944 it was released by a Soil Conservation Service (SCS) nursery in San Antonio. The SCS is today’s Natural Resources Conservation Services (NRCS), an agency of the United States Department of Agriculture (USDA). A 1949 photo of the nursery’ manager shows him measuring the root depth of KR bluestem—a stunning 9 feet. You can see the photo in the body of this online PDF.
From hot and cheesy casseroles to fancy Ford F150s, the King Ranch moniker is a popular one. The historic South Texas ranch, founded in 1853 by Captain Richard King, now covers 825,000 acres. During its more than 160 years it has endured its share of droughts. Efforts to find a grass that would withstand drought were spearheaded by Nico Diaz in the 1930s at the King Ranch. Described in “Meet the Grass That’s Eating Southeast Texas” as a “kind of Texas Johnny Appleseed, except he planted grass instead of fruit trees,” Diaz landed on this Chinese strain of grass as a solution, along with the other promising grass, the one that originated in South Africa and was ultimately named after the Kleberg branch of the King family.
Why KR bluestem has thrived
The drought-resistant qualities that made KR bluestem a Dust Bowl savior are exactly why it has survived and thrived in Texas. More Texas ranches planted the grass and the Texas Department of Transportation spread the aggressive grass along highways for erosion control. Those Texas winds we’re all so familiar with spread seeds like they spread wildfires. Extensive root systems can develop in just a few years, penetrate caliche, and grow many feet deep. One of the most insightful summaries of how KR bluestem came to dominate in Texas is found in a piece written by Ricky Linex, a wildlife biologist, with NRCS. From the article:
“Most impressive and helping to explain how it spreads is that seeds from a planted test area of KR travelled about 200 yards and established new plants. This grass can march across a pasture from seed that gets started in bar ditches and from old grass seed mixes containing both native and introduced plants. KR bluestem is a warm-season, deep-rooted bunchgrass that is adapted to most soil types in Texas. The lower stems and leaves often lay flat just above the ground turning upright at a node. Livestock are able to consume all of the upright growth, yet the plant maintains enough leaf material to continue photosynthesis even during severe over grazing that causes many natives to wither and die. A tougher adversary for native Texas plants would be hard to find in the state. I confess, in my early years with SCS and NRCS I added KR to seed mixes because it was the normal thing to do: it was easy to establish, cheap to buy, always available, everyone else was recommending it and it was adapted to many soil types. I have not recommended it for including in mixes for at least 15 years because of its invasive nature.”
How to control KR bluestem
“In short, Texans who treasure and now financially depend on wildlife and the native landscape have a big problem, and they don’t yet know how to fix it.”
– Forrest Smith, Texas Today: A Sea of the Wrong Grasses
How did KR bluestem, along with Kleberg bluestem, turn from savior to foe? As described in “Texas Today: A Sea of the Wrong Grasses,” Forrest Smith, with the Caesar Kleberg Wildlife Research Institute, spoke with his 85-year old Hill Country neighbor in 2009. The neighbor recounted to Smith that when he bought his place in the 1960s there were so many quail “you didn’t even need a bird dog to find them” but by the early 1980s “the quail were gone.” When Smith asked his neighbor what changed the frank response was: “Hell, I dunno, but just before that time everybody planted all the maize fields to coastal (bermudagrass), and that damn KR bluestem came in from the highway when they redid it.”
These invasive, non-native grasses have negatively impacted plant species diversity. As described by Smith, “bird and insect numbers plummet on exotic grasslands.” Moreover, catastrophic Texas wildfires may be “due in large part to the current sea of exotic grass” as they are “now a major part of the understory.”
Despite their abundance, these grasses are of very poor quality with minimal nutritional value— inadequate forage for livestock.
In a nutshell KR bluestem, along with Kleberg bluestem, are everywhere and, to be blunt, there’s little we can do to turn the ship around. While disking and herbicide have had some effect in reducing KR bluestem, without consistent follow-up treatments studies show that the grass eventually returns to pre-treatment levels. Moreover, the risk of damage to other wildlife caused by herbicides must be balanced against using it to battle KR bluestem. That being said, there are some actions you can take (and not take) to help stem the bluestem tide.
Don’t do anything. “Introduced Bluestem Grasses: Management on Native Lands” describes the following: “research has confirmed that many management techniques disturb plants and soils, which encourages the further spread of KR and Kleberg bluestem. KR bluestem has been observed to decrease in density on coarse (sandy) and drier soils when the land is left alone. Rather than creating a disturbance and encouraging these invasive grasses, there are situations where it may be best to leave the area alone and put effort into protecting areas that have not yet been invaded.”
Mowing (but with a big caveat). Mowing will not get rid of KR bluestem but it may help slow its spread if the mowing is done before the grass flowers and sets seeds. However (this is the big caveat), continuous mowing of KR bluestem causes the grass to shift its growth to parallel to the ground, spreading by rhizomes or stolons. “Introduced Bluestem Grasses: Management on Native Lands” notes: “Along many highway rights-of-way are examples of mowing that has led to the dominance of introduced bluestems. In areas mowed twice annually, introduced bluestems typically dominate, whereas the nearby rights-of-way generally left unmown have more native grasses and greater plant diversity, especially late in the growing season.”
Keep your equipment clean. If you do mow or disc in an infested area, make sure your equipment is clean before using the equipment in other areas. (Not unlike cleaning boats to prevent the spread of zebra mussels.)
Don’t feed from unknown sources. If you have livestock on your property, make sure you know what kind of grass hay you’re feeding.
Avoid exposing bare ground. Pay close attention to areas with non-native grasses and avoid exposing the soil near them. Bare ground gives them an opportunity to move in and become established.
Foster native grasses. Take care of your native grasses. Keep your eye out and routinely check for signs of invasive bluestems in other areas and take them out before they have a chance to become established.
