DATE. OF Station Bulletin 644 OUT Reprinted June 1994 IS Medus ahead (Taeniatherum information:A Review and Annotated Bibliography current PUBLICATION asperum Nevski): most THIS For http://extension.oregonstate.edu/catalog Ø Oregon State University Agricultural Experiment Station For additional copies of this publication, write: Publications Orders Agricultural Communications Oregon State University DATE. Administrative Services A422 Corvallis, OR 97331-21 19 OF OUT IS information: PUBLICATIONcurrent most THIS For http://extension.oregonstate.edu/catalog In July 1992 the warehouse storing Oregon Agricultural Experiment Station publications was destroyed by fire. SB644,originally published in June 1980, is hereby reprinted in its entirety. DATE. OF Agricultural Experiment Station Oregon State University Station Bulletin 644 OUT Reprinted June 1994 IS Medus ahead (Taeniatherum information:A Review and Annotated Bibliography current PUBLICATION asperum Nevski): most THIS For http://extension.oregonstate.edu/catalog Abstract Medusahead(Taeniatherurn asperumNevsld), a winter annual native to the Mediterranean region of Eurasia, has infestedseveral million acres of rangeland in the northwestern United States. It has been estimated carry- ing capacity for domestic livestock on infested ranges hasbeen reduced 75 percent. The review is a condensed summarization of the literature pertaining to medusahead. Four tables contain the types and effectiveness of variousDATE. con- trols applied to medusahead. The bibliography is the result of anextensive literature review on this species. OF OUT IS information: PUBLICATIONcurrent most THIS For http://extension.oregonstate.edu/catalog AUTHORS: Thomas 0. Hilken, Graduate Research Assistant; Richard F.Miller, As- sistant Professor, Rangeland Resources Program, AnimalScience Department, Oregon State University, Corvallis. Medusahead (Taeniatherumasperum Nevski): A Review and Annotated Bibliography Thomas 0. Hilken and Richard F. Miller Medusahead, a winter annual native to the Asia. The third, TaeniatherumDATE. asperum, our west- Mediterranean region of Eurasia, is one of the ern American weed, originally was found from primary range weeds in the western United States. Hungary through Ukraine to Tadzhikistan. It is a serious threat to rangelands with sparsena- The late 1800s is believed to be the approxi- tive plant communities, and more complex com- mate time of introductionOF of medusahead into the munities degraded to a iow seral state (71). An ag- United States(48). The plant probably was gressive competitor with other plants, medusahead brought to North America through dispersal of is a low-value forage species for livestock and wild- seed by imported animals. The first known speci- life. It has been estimated that the carryingcapac- men submitted to the University of California itv of rangeland for domestic livestock has been herbariumOUT was collected near Roseburg, Oregon, reduced by 75 percent after medusahead invasion in 1887 (11). In 1901, it was recorded from Steptoe (36). ButteIS in eastern Washington by Vasey (55), and in To decrease the negative effects of medusa- 1908, near Los Gatos, California, by Hitchcock head, wildiand managers need to know the general (39). ecology of the plant and practical control methods. After the initial introduction period, literature The objective of this paper is to present a brief citations increased with the rapid spread of medu- review of the literature pertaining to (1) origin sahead throughout the western rangelands. An and distribution, (2) environmental factors, (3) estimated 2.5 million acres were included within growth and nutritional characteristics, and (4) information:the periphery of known rnedusahead infestations control methods of medusahead. in Oregon (61). In Idaho, the weed spread from Medusahead (Taeniatherum asperum Nevski) a few isolated patches to more than 750,000 acres was classified in the United States as Elymus in 15 years (23). A total of 100,000 acres of range- caput-medusae L. because of a mistake (16). Ear- land were affected in the North Coast region of lier, Nevski, a Russian taxonomist, had classified California. Medusahead has infested 120,000 to the plant found on our range as Taeniatherum 150,000 acres in eastern Washington, and the asperum Nevski. The mistake wascurrent discovered by potential area is much greater (12). Medusahead Major (35) when hePUBLICATION visited Europe. Major pub- also has successfully invaded seral plant communi- lished the correct name, Taeniatherurnasperum ties on the edge of the interior basin of northeast- Nevski, in the United States, where it isnow gen- ern California, northern Nevada, and western erally accepted (16). McKell et al. (39), studying Utah (71). the ecotypic variationmost iii medusahead, concluded Medusahead probably has not reached its eco- that theTHIS best name for our plant seems to be logical limits (39). The plant successfully com- Taeniatherum asperurn (Simonkai) Nevski. petes and overlaps both in area and in local habi- Medusahead was introduced into the United tat ecology with two other exotic, annual range States fromFor the Mediterranean region of Eurasia, invaders, Bromus inollis L. in California and south- where it consists of three geographically andmor- ern Oregon and Brornus tectorurn L.If the require- phologically distincthttp://extension.oregonstate.edu/catalog taxa (39). The original Ely- ments of medusahead completely overlap those of mus caput-rnedusae grows on the Siberian penin- Bromus tectorwn, it could spread widely in the sula (35). Another species, Taeniatherum crini- Great Basin, where it now has a start in the north- turn, grows in North Africa and in the southern ern,low-altitude fringe of thisphysiographic Balkans through the Middle East to Soviet Central province (39). 3 (56). The Environmental Factors 500 plants per square foot on scablands head for the two sites Medusahead grows over a wide range of cli- average number of seeds per matic conditions. Annual precipitation on medusa- studied were 8.7 and 5.6, respectively. head sites throughout the four Western States Once medusahead becomesestablished,it ranges from 10 inches to 40 inches.Medusahead grows in dense stands,forming a mat of stems 2 to grows where precipitation occursduring f all, win- 5 inches thick (12). It is oftenthought that the high ter, and spring (36). Seasonal distributionof pre- silica content of medusahead maybe the reason cipitation is more significant than total precipitation it is slow to decompose (3).Evidence indicates in meeting the species moisture requirements(48). the dense litter cover is important inthe competi- tive relationship with cheatgrassbecause cheat- Medusahead grows where extended periods of under three inches of litter great cold are lacking (32). Moreover, someof grass fails to grow cover (9, 14).Medusahead's litter also is an ex- these climates are extremely hot. Medusahead re- and ties up soil quires a cold treatment and possibly light stimu- treme fire hazard in the summer nutrients ordinarily availablefor plant growth. lus after germination for seed formation to occur. the accumula- En one study, successful seed formation occurred However, it has been DATE.reported that tion of slowly decomposing litter maybe advan- after exposing seedlings to nightly temperatures of the loss of soil by 370 F. for 14 days in the field. The seedlings ma- tageous through safeguarding wind and water erosion in deteriorated areas sus- tured in the greenhouse (2) ceptible to erosionOF (61). Soil conditions suitable for growth of medusa- head are somewhat variable. Favorable environ- mental factors related to medusahead distribution Nutritional Characteristics were soils with a high clay content,well-developed Moisture content, crude protein,crude fat, profiles, and areas receiving run-off water from OUTcrude fiber, and lignin contents ofmedusahead are adjacent sites (7). Less susceptible to invasion comparable to cheatgrass and many desirable spe- were well-drained soils and thosedeveloped fromIS cies at similar growth stages(3). However, the rocks weathered to coarse-textured sands showing ash content of medusahead was found tobe much poorly developed profiles. Late maturity of the spe- greater than that of cheatgrassand many other cies in relation to other annual grasses and itssub- grasses. The ash ofmedusahead contained approx- sequent requirements for highwater-holding ca- imately 72 to 89 percent silica, andamounted to pacity clay soils are the accepted explanationfor more than 10 percentof the dry weight of the medusahead abundance on clay soils (71). plant. The high silica content ofmedusahead is information:thought to be the basis for its harshness.The long, barbed awns and sharp, hard seeds of the mature Growth Characteristics plant injure eyes and mouths of livestock. Medusabead is able to compete effectively with that desirable forage species because of the following Although numerous reports have indicated (1) it germinates in the medusahead isunpalatable, other investigators growth characteristics: have found heavy livestock grazing onimmature fall, roots continuing to grow all winter; (2) it is a fertiliza- proiffic seed producer; (3)current it produces a heavy plants in early spring (23, 30, 63). Range PUBLICATION tion, especially with N, offers apossible way to im- litter residue. prove the palatabilityof medusahead and to en- Medusahead germinates significantly faster and courage its early use by grazinganimals (30). An more fully than