Guide to King Ranch Bluestem Identification & Control

king ranch bluestem weeds

Type of Weed: Grassy Weed

Bothriochloa ischaemum

King Ranch Bluestem

King Ranch Bluestem (KR Bluestem) is a warm season, perennial grassy weed that is a common problem across Texas.

This weed is often found along roadsides, pastures, and has begun invading lawns. It is heat tolerant, drought resistant, and grows extremely fast.

This combination makes this weed difficult to control and near impossible to eradicate.

How to Identify

KR Bluestem is a deep-rooted bunchgrass that grows in tufts. This root system consists of underground rhizomes and aboveground stolons. Its stems arise from a somewhat flat crown, has the capability to spread, and can reach anywhere from 18-48 inches in height.

Stems are light green and turn to a straw color once matured. They are relatively hairless and produce long leaves that can reach up to 8 inches in length. These leaves are thicker near the collar and ligule and can have sparse, long hairs.

Stems will produce a 3 to 8 branched spikelet shaped seedhead that is purple to maroon in color. This weed begins to flower as early as June and reproduces by setting seed.

Control Methods

Control Difficulty: Very Difficult

Cultural control of mowing prior to the seedhead forming and flowering is a simple way to attempt to manage this invasive weed. KR Bluestem grows fast, making it appear as if you haven’t mowed in a while, when you just recently mowed. However, be careful to not mow too often. Too much continual mowing of this weed will enable it to change growth habits from erect to prostrate, allowing it to spread through rhizomes and stolons. Another cultural control option is attempting controlled burning. This isn’t fully effective as KR Bluestem can still resurface after a few years of a controlled burn. Lastly, high fertility soil usually discourages new seeds of KR Bluestem from germinating. This can be achieved through routine and proper fertilization throughout the year.

Mechanical control of digging may work for young KR bluestem that haven’t had a chance to spread or flower. Be sure to remove the entire root system, digging deep and wide enough to remove all the roots (and any stolons and rhizomes that could be present). For larger infestations, the turf may need to be dug up entirely with larger equipment. All bare spots of the lawn will then need to be replaced with new sod or have grass seeds sown, preventing other weeds from infiltrating these areas.

Chemical control is difficult as there are currently no selective pre or post emergent herbicides labeled for use to suppress or control this aggressive weed. Some may attempt to use non-selective herbicides, though this has shown to have limited results and isn’t fully effective (and will kill any turf and plants it comes in contact with).

Prevention Tips

KR Bluestem has proved to be an aggressive weed that is difficult to control and eradicate. The best way to prevent this weed from entering or sticking around in your lawn is to ensure it is dense and healthy. This can be achieved by mowing your lawn at your turf’s proper height, routine aeration and fertilization, along with proper irrigation.

For further help or guidance managing King Ranch Bluestem in your turf, give us a call today. Our team of highly trained technicians are experts with grassy weeds and can design a lawn care program to get your turf back to its proper health.
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