USDA United States Department of Agriculture - Field Guide for Managing Yellow and Caucasian (Old World) Bluestems in the Southwest Forest Southwestern Service Region TP-R3-16-36 October 2018 Cover Photos Top left — Yellow bluestem; courtesy photo by Max Licher, SEINet Top right — Yellow bluestem panicle; courtesy photo by Billy Warrick; Soil, Crop and More Information Lower left — Caucasian bluestem panicle; courtesy photo by Max Licher, SEINet Lower right — Caucasian bluestem; courtesy photo by Max Licher, SEINet Authors Karen R. Hickman — Professor, Oklahoma State University, Stillwater OK Keith Harmoney — Range Scientist, KSU Ag Research Center, Hays KS Allen White — Region 3 Pesticides/Invasive Species Coord., Forest Service, Albuquerque NM Citation: USDA Forest Service. 2018. Field Guide for Managing Yellow and Caucasian (Old World) Bluestems in the Southwest. Southwestern Region TP-R3-16-36, Albuquerque, NM. 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Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: [email protected]. USDA is an equal opportunity provider, employer and lender. Printed on recycled paper Yellow bluestem (Bothriochloa ischaemum (L.) Keng) Caucasian bluestem (Bothriochloa bladhii (Retz.) S.T. Blake, synonym: B. caucasica (Trin.) C.E. Hubb.) Grass family (Poaceae), Andropogoneae tribe Yellow and Caucasian bluestems are introduced identification of the two OWB species difficult in the bunchgrass species that are becoming invasive in spring. Positive identification generally can only be made southwestern States after successfully invading the Central after panicles have developed. Resources for identifying and Southern Great Plains. This field guide serves as the these two bluestem species can be found in the Photo U.S. Forest Service’s recommendations for management of Image Libraries subsection at the end of this document. yellow and Caucasian bluestems in forests, woodlands, OWBs are native to Eurasia, Africa, and Australia. They rangelands, desert, and desert scrub associated with its were first introduced into the U.S. in the early 1900s and Southwestern Region. The Southwestern Region covers have been planted widely throughout the Central and Arizona and New Mexico, which together have 11 national Southern Great Plains for forage and for erosion control in forests. The Region also administers 4 national grasslands disturbed areas such as roadside rights-of-way (ROWs). located in northeastern New Mexico, western Oklahoma, OWB seed is readily obtained from many seed companies. and the Texas panhandle. Growth Characteristics Description Both OWB species – Yellow bluestem (Bothriochloa ischaemum) and • Are warm-season, perennial bunchgrasses that are Caucasian bluestem (Bothriochloa bladhii) are perennial relatively shade-intolerant; typically, they have mid-grasses that belong to a group of non-native bluestems rhizomes (underground stems) and stolons (above- collectively referred to as Old World bluestems (OWBs). ground stems) under close grazing or cutting. Yellow The term Old World bluestem is a shared common name bluestem has a more rhizomatous growth form for approximately 65 species in the closely related genera relative to Caucasian bluestem’s bunchgrass of Bothriochloa Kuntze, Capillipedium Stapf, and (caespitose) growth form. Although the early growth Dichanthium Willemet. B. bladhii is used synonymously form of yellow bluestem is an erect bunchgrass, with B. caucasica, which is nearly similar in morphology older stands tend to form a sod. but has an uncertain taxonomy. • Produce spindly looking, flowering culms/tillers that Common names for yellow bluestem include King Ranch are 2–4 feet tall, depending on moisture. The two bluestem and Turkestan beardgrass; the most common species have reproductive and vegetative cultivars are King Ranch, Plains, Ganada, WW–Spar, and culms/tillers that are roundish with varying amounts WW–Iron Master. Caucasian bluestem is also called of hair; leaves typically are 0.25 to < 0.5 inches wide Australian beardgrass (or bluestem), forest bluegrass, and and 8-12 inches in length, flat or folded. purple plume grass. It has a single cultivar named WW-B. • Can initiate rapid growth in the summer and Dahl. OWB cultivars were developed from introduced reproduce earlier than native species, which actually germplasm and have been selected for different disease deters grazing. and insect threats, climates, and soil-site conditions. • Produce reddish-purple inflorescences; some cultivar Yellow bluestem derives its name from its yellow-green inflorescences may turn fawn to white-colored at culms and leaves. Caucasian bluestem has dense blue- maturity. Yellow bluestem’s inflorescence is a fan or green leaves, and some plants can be strongly aromatic. finger-like panicle; Caucasian bluestem has a panicle Close similarity to native bluestems makes early that is pyramidal or evergreen tree-shaped. 1 • Readily germinate from seed and establish Site/Distribution reproducing populations within one growing season; OWBs can infest both disturbed and non-disturbed sites; such features are highly desirable for hay production. however, they tend to establish more readily on disturbed Both OWB species are prolific seed producers, and sites. The two species can adapt to highly calcareous soils extensive seed banks can develop in soil. with high pH but do well on any well-drained soil. Yellow bluestem is best adapted for sandy loam to clay loam soils. Ecology In general, OWBs have relatively little cold tolerance, Impacts/Threats which makes them unable to withstand environment s with Once established, OWBs can be highly invasive and have extended periods of freezing winter temperatures. the potential to form biodiversity-inhibiting monocultures Caucasian bluestem is more tolerant to freezing and tends that can transform grassland vegetation at the community to occur in more northerly climes in the Midwest. Yellow and ecosystem levels of organization. OWB monocultures bluestem is more common in the southern U.S. and is lack the necessary variety in structure, seasonality of growth, winter-hardy in the Central Great Plains only to about 40 º and nutritional availability required to sustain a diverse N latitude. Both OWBs are found throughout Arizona and fauna. Floral diversity may be impacted directly by OWBs New Mexico, although Caucasian bluestem is relatively through physical displacement, competition, etc. Habitats of uncommon at this point in time. some Threatened and Endangered (T&E) species in particular can be threatened by OWBs. In combination with Spread other less desirable non-native grass species such as Sites planted or invaded by OWBs serve as the primary Lehmann lovegrass (Eragrostis lehmanniana), OWBs may source for further spread onto disturbed and non-disturbed form a complex that can act similarly to a monoculture. sites. In the Southwest, OWBs generally migrate away from infested roadsides or other disturbed areas in an Pastures and grasslands invaded by OWBs support fewer advancing front across pastures or native grasslands. If insects (a vital part of the food chain) as they lack forbs, unassisted, OWB seed has relatively limited dispersion which typically host more insects than wind-pollinated and will mostly establish seedlings close to parent plants. grasses. The reduction in forbs may particularly impact However, seeds readily disperse via mowing operations in native pollinators such as bees and butterflies. In addition, ROWs, vehicular traffic, flowing water, animals, and the loss in insect activity could ultimately lead to lower numbers and diversity of songbirds. winds moving across open terrain. Growth of stolons and rhizomes may also contribute to spread on a local basis. OWB infestations can alter carbon:nitrogen (C:N) ratios in soil and the composition of soil microbial communities, In the Southwest,