Station Bulletin 644 Reprinted June 1994

Medus ahead (Taeniatherumasperum Nevski): DATE. A Review and Annotated BibliographyOF

OUT IS

information:

PUBLICATIONcurrent most THIS For Agriculturalhttp://extension.oregonstate.edu/catalog Experiment Station Ø Oregon State University 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. Agricultural Experiment Station Oregon State University Station Bulletin 644 Reprinted June 1994

Medus ahead (Taeniatherumasperum Nevski): DATE. A Review and Annotated BibliographyOF

OUT IS

information:

PUBLICATIONcurrent most THIS For http://extension.oregonstate.edu/catalog Abstract

Medusahead(Taeniatherurn asperumNevsld), a winter annual native to the Mediterranean region of , has infestedseveral million acres of 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 . 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 . The third, TaeniatherumDATE. asperum, our west- Mediterranean region of Eurasia, is one of the ern American , originally was found from primary range in the western United States. Hungary through Ukraine to Tadzhikistan. It is a serious threat to with sparsena- The late 1800s is believed to be the approxi- tive 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 , medusahead brought to 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 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). 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 ( asperum Nevski) a few isolated patches to more than 750,000 acres was classified in the United States as 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 . 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 and in the southern ern,low-altitude fringe of thisphysiographic through the 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 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 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 either cheatgrass orbluebunch in vitro nutritive evaluationrevealed that imma- wheatgrass (Agropyronmost spicatum) (17). Medusa- ture medusahead had ahigher cellulose digestion head seedling roots begin post-germinationgrowth value as compared to a mixture ofdesirable annual THISin the fall, and grow all winter, thuseffectively range forage species (64). removing available soil moisture from nearby na- tive Forbunchgrasses and annuals.Medusahead also matures later than cheatgrass because its root sys- Control Methods tem remains functional for a longerperiod of time. Most studies on medusahead havebeen con- http://extension.oregonstate.edu/catalogit has Medusahead is a highly prolific seed producer cerned with control and suppression after (56) with germination rates of 98 percent(42). In become established. The results ofherbicide, me- dense stands, plant numbers range from 1,500 to chanical, burning, and fertilization treatments are 2,000 per square foot on valley bottom soils,and summarized in Tables I through IV. 4 Table 1.A summary of chemical treatments and their effectiveness in controlling medusaliead as reported in the literature

Herbicide Rate Comments Effectiveness Reference Atrazine 1/4 lb/A Applied in September + 1 27 1/2 lb/A Increased medusahead _2 70 1 lb/A Applied late fall + 62 1 lb/A Applied with 2,4-D (2 lb/A) + 74 2 lb/A + 5,61,63 2 lb/A Followed by application of a soil fumigant + 51 (methyl bromide) 2 lb/A Plus disc harrowing + 70

Amino triazol 2 lb/A 90% 8 61b/A 100% 8 high rate Cost prohibitive + 2

Bromacil 1 lb/A Applied late fail DATE.+ 62 CDAA 2,4,8 lb/A Applied in September - 27 21b/A - RNG OF - 2 CDEC RNG - 2 CIPC 6 lb/A With discing 100% 8 81b/A 90% 8 2,4,8 lb/A OUT - 27 high rate Cost prohibitive + 2 RNG + 48 RNC Gave outstanding controlIS on an annual grassland + 34 Dalapon 1 lb/A - 34 2 lb/A + 48, 61, 63 2 lb/A Applied 30 days after emergence 96% 26 2 lb/A Applied late April (boot stage) 90% 41 2 lb/A Applied mid-April to mid-May effective by burn- + 19 ing litter before application 2 lb/A With or without discinginformation: 100% 8 3 lb/A May cause damage to perennials + 61 3 lb/A Applied 30 days after emergence 100% 26 3 lb/A Applied between germination and boot stage + 12 3 lb/A Applied in April + 18 41b/A 97% 41 4 lb/A + 33, 36 2-6 lb/A Combined with disc harrowing and furrowing + 70 lowrate current + 2 PUBLICATIONRNC Effective if combined with other control measures + 58 RNG Followed by 2,4-D + 59,60

DNBP RNC With 40 gal. weed oil + 60 gal. H20 + 36 Dowpon most3 lb/A Applied with 2,4-D + 59 DiuronTHIS 2 lb/A Plant composition changed from medusahead to + 77 cheatgrass For 20 lb/A Practical to use on small patches of medusahead + 19 EPTC 2,4,8 lb/A Applied in September + 27 4lb/A + 36 http://extension.oregonstate.edu/catalogRNG Gave outstanding control on an annual grassland + 34

1 + = treatment was effective 2_ = treatment was not effective BNG rate not given in report 5 Table 1. (Continued)

Herbicide Rate Comments Effectiveness Reference IPC 4 lb/A Applied with .75 lb/A 2,4-D (fall) + 62 61b/A 50% 8 61b/A With discing 100% 8 81b/A 100% 8 high rate Cost prohibitive + 2 ENG + 48 Isocil 1 lb/A + 61, 63 Monuron 1/2 lb/A 34 1/2, 1,2 lb/A Applied in September - 27 Paraquat 1/2 lb/A Applied in winter + 28 RNC - 62, 70, 16 1/2 lb/A Two- stage - 75 Picloram 3 lb/A Pre-emergence application sufficiently suppressedDATE.+ 73 medusahead Siduron 3 lb/A Pre-emergence application sufficiently suppressed + 73 medusahead OF RNG In the greenhouse, controlled seedlings of medu- + 68 sahead Simazine 1/2, 1,2,4 + 27 lb/A 2-4 lb/A + 36 RNG Effective control on an annualOUT grassland + 34 IS

information:

Table 2.A summary of mechanical treatments and their effectiveness incontrolling medusahead as reported in the literature Reference Mechanical Comments Effectiveness Plowing (moldboard) plowing alone 95% 8 effectivecurrent if combined with other control measures +1 58, 60 PUBLICATIONplowing with herbicide 100% 8 plowing in spring + 48 effective if first burned + 19 spring tillage, summer fallow + 12 effective only on limited areas + 61 most spring plowing followed by discing + 16 THISDiscing (harrow) discing alone 50% 8 disced in spring + 48,61 disc-harrowed and summer fallowed + 70 For effective if combined with other control measures + 58, 60 discing with herbicide 100% 8 effective if first burned + 19 http://extension.oregonstate.edu/catalogcombined with seeding and fertilization + 36 11 Mowing + plus grazed ± 63 + = treatment was effective 6 Table 3. A summary of burning treatments and their effectiveness in controlling medusaheadas reported in the literature Burning Comments Effectiveness Reference On an annual grassland 60-90% 18 On an annual grassland +1 11,40, 43 Burning alone 48 Burning alone in spring 8 Increase forage availability + 28 Downslope and into wind + 42 Increased medusahead 78 Plus tillage and fall seeding + 12 Plus tillage and herbicide + 59 Plus intensive range improvement practices + 36 Burning effective if proceeded by other control measures + 60 Burning will enhance the effectiveness of tillage and herbicidal treat- + 58 ments 1+ = treatment was effective DATE. = treatment was not effective Table 4. A summary of fertilization treatment and its effect onOF medusahead Fertilizer Rate Comments Reference NH4NO3 150 lb/A Reduced medusahead by increased from and 33 grasses N 85 lb/A Improve palatability of medusaheadOUT 61 35 lb/A Improve palatability of medusahead 62 160 lb/A 90% utilization 3 20 lb/A 40% utilization IS 3 60 lb/A Applied as 16-20-0 fertilizer, improved palatability 29 150 lb/A Reduced the soil moisture below the field capacity early in the season 38 (near the first of April) 40 lb/A Produced lush growth P 150 lb/A Treatment was similar to the check plot 38 Single 400 lb/A Improve palatability information:of medusahead 18 super phosphate Treble 100 lb/A Reduced medusahead by increased competition from forbs and 33 Super grasses phosphate N+P 150 lb/A-N Combination of nitrogen and phosphorus resulted in an interaction that 38 200 lb/A-P currentgave increased yield of forage N+P PUBLICATION375 lb/A Improved utilization when consumption was forced 30

Briefly, dalapon and atrazine have beenproven growth of medusa1ead is absent. Burning is most to be effective in controllingmost medusahead. Spring effective when burns are slow and seed moisture tillageTHIS with summer fallow has given bettercon- above 30 percent or when used with trol if combined with chemical treatment. Results and tillage practices. On annual grasslands, range of burning trials have been highly variable, and fertilization has been effective in reducing the den- when usedFor alone, satisfactory results were not al- sity of medusahead by competition from fertilized ways obtained. The most important benefit from forbs and grasses. Livestock have been known to burning is removalhttp://extension.oregonstate.edu/catalog of the dense mat of litter that relish fertilized immature medusahead plants. Any impedes tillage, lowers the effectiveness of herbi- control practice that involves a herbicide, mechani- cides, and prevents preparing a high-quality seed- cal, or burning treatment, should include estab- bed. It also has been reported that livestock will lishment of adapted perennial grasses to prevent graze medusahead more freely where the old re-establishment of medusahead. 7 Literature between BAKER, H. C. 1972. Migration of Weeds, p. 327- BRANNON, T. A. 1972. Some interactions nitrate-nitrogen and temperature in portionsof the 347. IN: , Phytogeography and Evolution. Wash- D. H. Valentine, ed. London. Academic Press Inc. life cycle of four range grasses. M.S. Thesis. (London) Ltd. ington State Univ., Pullman. 69 p. Under conditions of low nutrient nitrate,medusa- Species discussed include Cynodon dactylon, Penni- head produced more top growth relative to its po- setum clandestinum, Trifolium repens, Sorghum spp., of Leucaena tential than did cheatgrass. Slow decomposition Prosopis glandulosa, Acacia farnesiana, medusahead litter tied up soil nitrogen longerthan glauca (= L. leucocephala) and Taeniatherum caput- cheatgrass litter. The combination of these twochar- medusae. It is pointed out that removal of a weed acteristics of medusahead can at least in partexplain (e.g. Hypericum perforatum in N. California by bio- established cheat- logical control) must be followed by resowing with how medusahead is able to invade desirable species if the vacant niche is not to be filled grass stands. by other weeds. CHRISTEN, M. D., J. A. YOUNG, and R. A.EVANS. 1974. Control of annual grasses and revegetationin BOVEY, R. W. 1959. A study of growth, composition 27:143- and environmental factors in the control and utili7a- ponderosa pine woodlands.DATE. J. Range Manage. tion of Elymus caput-medusae L. M.S. Thesis. Uni- 145. versity of Idaho, Moscow. 97 p. Atrazine (1.12 kg/ha) controlledTaeniatheruni as- Herbicides CIPC, IPC, amitrol, and dalapon were perum and Broinus tectorumsufficiently to permit the establishmentOF of perennial wheatgrass(Agropyron found to be effective in controlling medusahead . ponderosa) CIPC, IPC, and amitrol are required at higher rates intermedium) in a ponderosa pine (Pinus woodland previously burned in . Autumn ap- and consequently costs become prohibitive. Dalapoii survival of P. proved to be the most desirable herbicide tested plication of atrazine greatly improved because of the effective low rate per acre and the ponderosa and bitterbrush (Purshia tridentata)seed- lings transplanted to plots the followingspring. P. lower costs involved. CDAA and CDEC were found OUTtridentata seedlings established naturally in areas to be ineffective. Greenhouse studies on nitrogen fer- treated with atrazine. The herbicide treatment re- tilization revealed 40 pounds/acre of actual nitrogen and, appar- produced lush growth which appeared to be attrac- duced competition from annual grasses, IS ently, created a desirable habitat for seedcaching by tive to livestock. Seedlings exposed to nightly tempera- rodents. Higher rates of atrazinecontrolled most tures of 370 fahrenheit or lower for approximately 14 growth of days resulted in vernalization and subsequent floral herbaceous vegetation and promoted the P. ponderosa seedlings. Failure to establishperennial initiation. Medusahead grown on arid, neutral, and annual grasses. alkaline soils was not limited to any one soil type. grasses resulted in reinvasion by Ensiing medusahead did not produce a safe palatable DAHL, B. E. 1967. Environmental factorsrelated to feed because of the high silica content. Chemical medusaheaddistribution.M.S.Thesis,Univ.of compositionstudies on medusahead and downyinformation:Idaho, Moscow, Idaho. 122 p. brome (Bromus tectorum) revealed moisture, crude fat, crude fiber, protein, and lignin contents were Multiple correlation analysis revealed that next to reasonably equal between the two species at similar competition from other vegetation, thestructural de- stages of growth. The ash content of medusahead velopment of the soil B horizon and thetopographic generally was found to be more than double that of position were the most influential sitecharacteristics in determining medusahead andcheatgrass adapta- downybrome. Control by grazing is improbable be- by medu- cause of the inherent unpalatabilityof this species. bility. Soils poorly aerated were preferred sahead. Soils with well-developed profiles were us- BOVEY, R. W., D. Lecurrent TOURNEAU, and L. C. ually dominated by cheatgrass.Medusahead pre- ERICKSON.PUBLICATION 1961.The chemical composition of ferredgrurnusolsandothermontmorillonite-typc medusahead and do brome. Weeds 9:307-311. clay soils. Azonal and Entisol soils were not suscep- tible to medusahead invasion. No relationshipbe- The moisture, crude protein, crude fat, crude fiber, moisture or and lignin contents of medusahead (Elymus caput- tween medusahead or cheatgrass to a medusae) were comparable to that of downy brome temperature gradient could be detected,but medusa- and manymost desirable grass species. The ash content of head was limited to the more mesic topographic po- medusahead, however, was found to be much greater sitions in arid areas. In the 9- to 11-inchprecipita- THISthan that of downy brome and of many other tion zone, a strongly developed clay Bhorizon within contained silica 10 to 12 inches of the soil surface wasseemingly re- grasses. The ash of medusahead soil amounting to more than 10 percent of the dry weight. quired for medusahead occupancy. Available For of moisture in areas with less than 9.5 to 10inches of The high silica content of medusahead is the basis for its harshness and may explain partially its unattrac- annual precipitation does not endure long enough also may medusahead to complete itslife cycle. Greenhouse tivenesshttp://extension.oregonstate.edu/catalog to livestock. The high silica content water than be the reason why the plant is slow to decompose in pot studies revealed cheatgrass used more medusahead until it matured; but because of later the field. Nitrogen fertilization increased forage con- required sumption by cattle and horses. Medusaheadsilage, phenologicaldevelopment,medusahead whether pure or modified with additives, was unac- water for a longer period andhad a higher total ceptable to . requirement. 8 DAHL, B. E., and E. W. TISDALE. 1975. Environ- soil movement and pitting the soil surface compared mental factors related to medusahead distribution. J. to broadcast sowing on the surface of smooth soil. Range Manage. 28:463-468. These conditions maintained temperatures and soil The extent to which medusahead wildrye (Taenia- and atmospheric moisture in the range required for therum asperum = T. caput-medusae), an annual establishment. grass of low forage value, had spread at the expense of FURBISH, P. 1953. Control of medusahead on Cali- perennial grasses on depleted Idaho rangelands was fornia ranges. J. Forest 51:118-121. studied in a number of areas varying in altitude, soil structure, and climate. Factors favorable to medusa- Medusahead, a weedy annual grass, has become es- head encroachment were soils with a high clay tablished on northern California ranges. Preliminary content, well-developed profiles, and areas receiving results indicate controlled burning to be an economic- run-off water from adjacent sites. Less susceptible ally effective method. Mowing and chemicals may to invasion were well-drained soils and those devel- have a place in the control program. Its spread to oped from rocks that weathered to coarse-textured new areas may be minimized by proper handling of sands showing poorly developed profiles. These soils livestock. tended to be dominated by cheatgrass (Bromus tec- GOEBEL, C. J., J. R. NELSON, and C. A. HARRIS. torum), a grass with some value as a livestock forage. 1969. Medusaheada threat to Washington range- Avoiding depletion of native perennial vegetation was land. Washington State Univ.,DATE. Ext. Serv. Cite. 359. helpful in resisting invasion by medusahead on sus- 3p. ceptible soils in areas at risk. Medusahead has infested 120,000 to 150,000 acres in ERICKSON, L. C., C. LAMBERT, and R. S. PAR- eastern Washington. The forage has an unusually ISH. 1956. Chemical and cultural treatments for the high silica content,OF making it low in nutrient value. control of medusahead rye. Res. Prog. Rep. WWCC. Also, the sharp awns frequently cause punctures and p. 20-21. infection of eyes, throat, and other tissues in live- stock. Once medusahead becomes established,it Cultural treatments were definitely helpful in control- grows in dense stands, forming a mat of undecom- ling medusahead. A moldboard plow gave approxi- posed stems two to five inches thick. The dense litter mately 95 percent control, and plowing in combina- isOUT an extreme fire hazard in the summer, ties up soil tion with herbicides attained 100 percent control. nutrients ordinarily available for plant growth, and Discing alone gave approximately 50 percent con- shades or smothers out seedlings of valuable forage trol; while discing plus dalapon or amino triazole at IS species. Application of 3 lbs. of dalapon in 10 to 20 a 2 lb/A rate gave 100 percent control. Six pounds gallons of water per acre was effective in controlling per acre of IPC or CIPC were necessary for 100 per- medusahead if applied before the boot stage but after cent control on disced areas. Burning alone in the most of the medusahead had germinated. Spring till- early spring attained little control, although it gave an age with summer fallow usually gives better control additive effect in combination with the herbicides, as than chemical treatment. Burning helps destroy seed compared to check treated areas. Dalapon at all rates and reduce next year's stand, but should be followed 2 pounds and upgave 100 percent control. Am- with tillage for satisfactory control. Any control op- ino triazole gave 100 percent control at the 6-lb. rateinformation:eration should include establishment of adapted per- and approximately 90 percent control at the 2-lb. rate. eimial grasses to prevent re-establishment of medu- It took 8 lbs. per acre of IPC to give 100 percent sahead. control, and the 6-lb. rate gave approximately 50 per- cent control. Eight pounds of CIPC gave approxi- GOEBEL, C. J., and C. BERRY. 1976. Selectivity of mately 90 percent control. range grass seeds by local birds. J. Range Manage. 29:393-395. EVANS, R. A., and J. A. YOUNG. 1970. Plant litter On steep or rocky areas in depleted semi-arid Pacific and establishment of alien annual weed species in Northwest range, where broadcast rather than me- rangeland communities. Weed Sd.current 18:697-703. chanical sowing must be practiced, selective feeding Plant litter thatPUBLICATION covers the soil surface acts as a layer by local birds may alter the balance of desirable for- of insulation, moderating temperature and moisture, age species. In studies of six perennial grasses the and creating favorable microsites for germination and small seeds of Poa ample and ovina were establishment of annual weed species on rangeland selectedinpreferencetothoseof larger-seeded communities. Litter cover is an important factor in Agropyron spp. by wild birds (25 species were ob- succession amongmost annual species which culminates in served in 1969). Seeds least preferred were those of THISdominance by downy brome and medusahead in the annuals Bronzus tectorum and Taeniatherum as- these communities. perum. Resowings under litter cover were success- fully hidden from most birds until germination. EVANS,For R. A., and J. A. YOUNG. 1972. Microsite HARRIS, C. A. 1965. Medusahead competition. p. requirements for establishment of annual rangeland 66-69. IN: Proc. of the Cheatgrass Symposium, Vale, weeds. Weed Sci. 20:350-356. Oregon. (Portland) Bureau of Land Management. In trials on clayhttp://extension.oregonstate.edu/catalog and sandy loam soils during 1969-71, Evidence indicated that dense litter cover which ac- germination and establishmentof downy brome cumulated under medusahead stands was important (Bromus tectorum), medusahead (Taeniatherum as- inthecompetitiverelationshipwithcheatgrass. perum), and tumble mustard (Sisymbrium alt isi- Cheatgrass failed to grow under three inches of litter mum) were increased when buried 1 cm deep, by cover. 9 HARRIS, C. A., and A. M. WILSON. 1970. Compe- HARWOOD, L. 1960. Programs to control medusa- tition for moisture among seedlings of annual and per- head. Proc. Calif. Sec., Soc. Range Manage. Fresno, ennial grasses as influenced by root elongation at low Calif. p. 45-49. (Mimeo release.) temperature. Ecology 51:530-534. Dalapon was applied at rates varying from 2 to 8 Rapidly elongating Bromus tectorum and Taenia- lb/A. Rates higher than 3 lb/A gave 95 to 100 per- therum asperum roots penetrated the soil ahead of cent kill of medusahead. Fall discing, followed by Agropyron spicatum roots and used available mois- seeding Mt. Barker sub-clover at 9 lb/A and adding ture. In contrast, Agropyron desertorum roots pene- 400 lb/A of single super phosphate, reduced the trated the soil almost as rapidly as B. tectorurn and number of medusahead seed heads per square foot T. asperum and remained in favorable moisture. from 165 to 24. Medusahead was reduced 60 to 95 These differences in root penetration resulted in lower percent by burning. All burns should be downhill leaf water potentials and poorer survival in A. spicatum with a minimum amount of wind. Where it is eco- than in A. desertorum. The results suggest that in nomically feasible, burning should be followed by areas where root growth occurs at low temperatures reseeding and fertilization. and where lands are infested with B. tectorum and T. asperum, seedlings of A. desertorum would be HIGGINS, R. E., and P. J. TORELL. 1960. Medusa- more successful than seedlings of A. spicatum. head: range menace. Univ. of Idaho Agr. Exp. Sta., Ext. Bull. 331. 4 p. DATE. Medusahead competition is most severe where there HARRIS, C. A., and C. J. GOEBEL. 1976. Factors is overuse of desirable species. The long, rough awns in plant competition in seeding Pacific Northwest and sharp, hard seeds cause injury to the eyes and ranges. Washington State Univ. Agr. Exp. Sta., Bull. mouths ofOF both sheep and cattle. The awned seeds 820. 21 p. are blamed for sores in the flanks of sheep.Wool is Medusahead is quite similar to cheatgrass in life his- docked because of the presence of medusahead seed. tory and ecological adaptation. However, several com- Temporary control of the weed can be accomplished petitive advantages were attributed to medusahead by moldboard plowing, disc, plowing, or by applying which in combination could result in the displace- 2 lbs. of dalapon per acre from mid-April to early ment of cheatgrass by medusahead. Medusahead OUTMay. Treatments are more effective if the medusa- seed had greater germinability under adverse condi- head litter is first removed by burning. However, un- tions of low temperature and high moisture tension less a forage species can be established to compete than cheatgrass or bluebunch wheatgrass. Medusa-IS with medusahead, the area will be quickly reoccu- head grew faster than cheatgrass at iow tempera- pied by the weed. tures and matured seed about two weeks later. Me- dusahead litter accumulated to depths of 5 to 10 cm, HIRONAKA, M., and E. W. TISDALE. 1958. Rela- limiting germination and growth of cheatgrass by re- tive rate of root development of medusahead and ducing nitrate release. Medusahead was more vigor- cheatgrass. Res. Prog. Rep. WWCC. p. 28. ous at low nitrate levels than cheatgrass. After germ- ination in the fall, medusahead and cheatgrass roots The aerial portion of medusahead and cheatgrass continued to grow throughout the winter. Medusa-information:changed little from December to March, while root head roots reached 100 cm depths by early Febru- length increased significantly during this period. Root ary; cheatgrass roots reached 90 cm by mid-March. elongation was similar in the two species from Decem- Medusahead root diameter is relatively large, and ber to March. No root growth took place when max- cells were thick-walled throughout. It was reasoned imum-minimum temperatures under the litter were that this heavier suberization makes possible translo- 37° and 19° F. Because of early maturity of cheat- cation of soil water throughout relatively hot, dry grass, differences in root length in the spring were surface soil layers, accommodating a later phenology difficult to evaluate. However, the study did indicate in medusahead. Treatmentcurrent of medusahead with para- that medusahead may have a slight advantage over quat on burnedPUBLICATION plots gave no better control than with- cheatgrass for soil moisture. out the chemical treatment. Spring plowing followed by discing gave the best control of medusahead. HIRONAKA, M. 1961. The relative rate of root de- velopment of cheatgrass and medusahead. J. Range most Manage. 14:263-267. HARRIS, C. A. 1977. Root phenology as a factor The relative rate of root development of medusahead THISof competition among grassseedlings.J.Range and cheatgrass was studied. Rate of vertical root Manage. 30:172-177. penetration of the two annual grasses was about Medusaheadgerminatedsignificantlyfasterand equal, but cheatgrass reached maximum branching a moreFor completely than either cheatgrass or bluebunch few weeks earlier than medusahead. Maximum root wheatgrass. Cheatgrass and medusahead seedling development coincided closely with time of full in- roots began post-germination growth at a more rapid florescence for the two species. Because medusahead rate thanhttp://extension.oregonstate.edu/catalog bluebunch wheatgrass and continued thus matures later, its root system remains functional for all winter. Medusahead roots grew slightly faster a longer period than those of cheatgrass. Whenthe than cheatgrass roots. Cheatgrass and medusahead two species are growing together, the water require- roots effectively removed available soil water at depths ment for cheatgrass must be satisfied before medusa- where bluebunch wheatgrass roots were growing. head is able to complete its life cycle. 10 HIRONAKA, M., and E. W. TISDALE. 1963. Sec- densities were low to moderate, the proportion of ondary succession in annual vegetation in southern total leaf length produced by squirreltail decreased Idaho. Ecology 4:810-812. steadily with time. Secondary succession inside an exciosure was fol- lowed from 1938 to 1961. Bromus tectorum became KAY, B. L. 1983. Effects of dalapon on a medusa- the dominant species a few years after the sitewas head community. Weeds 11:207-209. protected from rabbits, replacing the annual. Dalapon (2,2-dichloropropionic acid) was applied to stage in plant succession. In turn, Bromus tectorum a predominately medusahead (Elymus caput-medusae was followed by Sitanion. hystrix, a relatively short- L.) community at rates of 1, 2, 3, 4, and 5 lb/A and at lived perennial grass. From the viewpoint of live- four stages of growth. Low rates of dalapon gave bet- stock forage, conversion from Bromus tectorum dom- ter control when applied at early growth stages than inance to that of Sitanion may not always be war- the same rates applied later. Reduction in total ground ranted because of the relative good forage qualities of cover was less from December and February appli- the brome. In the case of areas dominated byan an- cations than from March applications. Dalapon at 3 nual grass of low livestock preference, such as Ely- lb/A applied 30 days after emergence gave 100 per- mus caput-medusae (medusahead), replacement with cent kill of medusahead. Two lb/A gave 96 percent or Sitanion in areas that cannot be artificially seeded with better control when applied during the vegetative other perennial forage species would be highly de- stage (December, February, March). Both 2 and 3 sirable. lb/A applied in December,DATE. and 2 lb/A in February left a favorable balance of species among the re- HIRONAKA, M. 1965. The medusahead problem,p. maining forage plants. 62-65. IN: Proceedings of the Cheatgrass Symposium, Vale, Oregon. (Portland) Bureau of Land Manage- KAY, B. L., andOF C. M. McKELL. 1963. Pre-emerg- ment. ence herbicides as an aid in seeding annual range- In the sagebrush grass region, medusahead represents lands. Weeds 11:260-264. the highest annual grass stage in secondarysucces- Simazine, EPTC, and atrazine were shown to aid the sion. Medusahead is better able to make fuller utili- establishment of rose clover (Trifolium hirtum All.) zation of site resources than cheatgrass. Replacement andOUT harding grass (Phalaris tubcrosa Hitch.) by re- of cheatgrass is apparent because of the higher re- ducing competition from resident annual plants, pri- productive success of medusahead. Cattle willgraze marily medusahead (Elymus caput-medusae L.). The medusahead more freely where the old growth of ISsuccess of pre-emergence herbicides was shown to medusahead is absent. With heavy use, old growth depend on fall precipitation in amounts great enough does not accumulate and greater use of medusahead to permit seed germination and plant growth before can be obtained during the pre-head stage. winter temperatures became limiting. HIRONAKA, M., and B. W. SINDELAR. 1973. Re- KAY, B. L. 1965. The medusahead problem in Cali- productive success of squirreltail in medusahead in- fomia.what progress is research making? p. 74-80. fested ranges. J. Range Manage. 26:219-221. IN: Proceedings of the Cheatgrass Symposium, Vale, Squitreltail(Sitanion hystrix),a native perennial information:Oregon. (Portland) Bureau of Land Management. bunchgrass, exhibited an ability to become estab- Medusahead (Elymus caput-rnedusae L.) acreage in lished in medusahead dominated ranges in Idaho. California is still growing in both the Mediterranean The reproductive success of squirreltail seedlings and High Desert areas. Paraquat sprayed during the averaged 2.6 percent after 18 months in plots that winter at .5 lb/A removed medusahead from range were broadcast seeded on unprepared seedbeds. seedings of desirable clovers. A heavy litter residue, Rapid physiologic development of squirreltail seed- always present with medusahead, is desirable. Para- lings appeared to be the most important characteristic quat remains on the litter and controls new weeds as to explain its successful establishment.current they intercept the litter. Weed control in minimum litter accumulation was only temporary. Medusahead HIRONAKA, PUBLICATIONM., and B. W. SINDELAR. 1975. burning removed the litter and made the new for- Growth characteristicsof squirreltailseedlingsin age crop available to livestock. competition with medusahead. J.Range Manage. 28:283-285. LUSK, W. C., M. B. JONES, P. J. TORELL, and In the glasshouse, mosta competition study among several C. M. McKELL. 1960. Utilization and palatability of densities of medusahead (Taeniatherum asperum) medusahead by sheep as affected by growth stage andTHIS a constant number of squirreltail (Sitanion hy- and soil fertility. Proc. Calif. Sec. Soc. Range Man- strix) seedlings was conducted over an 85-day period. age. Fresno, California. p. 41-45. (Mimeo release.) At the end of the experiment the average root weight Sheep appeared to prefer fertilized strips of medusa- of squirreltailFor was greater than that of medusahead, head, and it was apparent that heavy grazing was even though the average shoot weight of medusahead damaging the plant. Measurements indicated that 25 was greater in all treatments where the two species percent of vegetation in the fertilized strip was medu- were grown together.http://extension.oregonstate.edu/catalog Squirreltail contributed only a sahead, compared to 65 percent medusahead in the small proportion of the total leaf length produced in unfertilized strip. Results of this study showed medu- containers with high densities of medusahead, but sahead may be eaten by sheep during most of its the proportion remained relatively constant through- growth stages, particularly before the formation of out the experiment. In treatments where medusahead seedheads. 11 LUSK, W. C., M. B. JONES, P. J. TORELL, and MAJOR, J., C. M. McKELL, and B. L. KAY. 1958. C. M. McKELL. 1961. Medusahead palatability. J. Control of medusahead (Elymus caput-medusae L.) Range Manage. 14:248-251. by several pre-emergence herbicides and competi- A grazing test was conducted with sheep to investi- tion with resident and reseeded species. Res. Frog. gate the palatability of medusahead on fertilized and Rep. WWCC. p. 26-27. unfertilized annual range. The results indicated that: EPTC, CDAA, CIPC, simazine, dalapon, and monu- (1) sheep, given a free choice, did eat medusaheaci ron were applied in the fall on a California annual as long as it was green, (2) sheep held in a small grassland dominated by medusahead. Rates of appli- plot area ate some medusahead even when it had cation were applied at three geometrically increasing headed out and dried,(3) heavy grazing in the rates starting with 1/2 lb/A for monuron and simazine, spring resulted in a thinned stand of medusahead at 1 lb/A for dalapon, and 2 lbs/A for EPTC, CDAA, and maturity as compared to a dense stand of medusa- CIPC. After 4.35 inches of rain, rose clover(Trif0- head resulting from light or no grazing, and (4) con- liutn hirtum) and Harding grass (Phalaris tuberose) sumption with forced grazing showed that fertilized were band seeded at about 8 lbs/A of each, with 200 medusahead was grazed more than unfertilized medu- lbs/A of 16-20-0 fertilizer. EPTC, CIPC, and si- sahead since a greater amount of medusahead was mazine gave effective control of resident grasses, in- taken from the fertilized plots early in the season. This cluding medusahead. Simazine had eliminated most resulted in less medusahead on the grazed-fertilized other vegetation as well. The EPTC and CIPC plots areas late in the season as compared to grazed- had excellent bur cloverDATE. (Medicago lisfida) stands unfertilized areas. However, palatability measured by from resident seed. Plots treated with CDAA, dalapon, esophageal fistula technique suggested there was no and monuron differed little from the checks. difference between the percentage of xnedusahead in the diet from fertilized and unfertilized areas. MAJOR, OFJ. 1960. Medusaheadorigin and current status.Proc.Calif.Sec.Soc. for Range Manage. Fresno, California. p. 35-39. (Mimeo release.) MacLAUCHLAN, R. S., H. W. MILLER, and 0. K. These species of medusahead were identified from the HOGLUND. 1970. Lana vetch for medusahead con- standpoint of morphology and geographical distribu- trol. J .Range Manage. 23:351-356. tion. The original Ely?nus caput-medusae that Liz- Overseeding with Lana vetch (Vicia dasycarpa Ten.), OUTnaeus named grows in , , and southern a self-perpetuating annual legume, appeared to sup- . This Medusahead taxon was called subspecies, press medusahead. Lana vetch can be successfully bobartii by Ascherson and Graebner. The second spe- established without seedbed preparation, offering ISa cies has been called crinitus. It occurs from North practical method of controlling medusahead on rough Africa, the southern Balkans, through the Middle East terrain. to Soviet . The third species, our west- ern American weed, has been called a.sper. It occurs from Hungary through the Ukraine to Tadzhikistan. MAJOR, J. 1958. Responses of medusahead (Elymus The generic name Taeniatherurn was invented by Nevski, a Russian taxonomist. Taeniatherum asperum caput-medusae L.) to different planting dates. WWCC. is now the accepted name of our medusahead be- Res. Prog. Rep. p. 29. information:cause of the morphological and geographical differ- Plantings were made monthly from August 1956 to ences of the three species. March 1957. One-half the plants were kept in a greenhouse and the other half outside. Medusahead MAJOR, J., C. M. McKELL, and L. J. BERRY. 1960. requires cold treatments after germination for normal Improvement of medusaheadinfestedrangeland. completion of its life cycle. The short days of autumn Calif. Agr. Exp. Sta., Ext. Serv. Leaf. 123. 3 p. also provide a necessary stimulus. Medusahead is invading California's rangelands at a serious rate. Small spot infestations must be con- current trolled, even at a high cost, to ensure against spread MAJOR, PUBLICATIONJ., and C. M. McKELL. 1958. Relations of of the weed to uninfested areas. Chemicals applied at medusahead (Elymus caput-medusae L.) to fertiliza- the proper time and rate are effective in controlling tion, dalapon, and soil moisture. Res. Prog. Rep. medusahead. Reseeding spot infestations is a neces- WWCC. p. 27. sary follow-up treatment. On widespread, long-estab- NH4NO3 at 150 lbs/A of N alone and with P at 100 lished stands of medusahead, chemical control is not lbs/A as treblemost superphosphate gave good yield re- economically feasible. Under such conditions, the spouse of medusahead and other weedy annuals. In more productive locations should be chosen for im- THISApril, medusahead was more abundant on the ferti- provement by burning and cultivation, combined lized than unfertilized piots. In June, medusahead with seeding legumes, fertilizing with phosphorus or was less abundant on the fertilized plots because of sulfur, or seeding aggressive, locally adapted perennial increasedFor rates of moisture depletion. Medusahead grasses. Seeding operations should be followed by did benefit from late spring moisture on plots not proper livestock management. fertilized because it had not been reduced in density by competitionhttp://extension.oregonstate.edu/catalog from fertilized forbs and grasses. The MALLORY, J. 1960. Soil relationships with medusa- few medusahead plants left on the dalapon-treated head. Proc. Calif. Sec., Soc. Range Manage. Fresno, sites responded more to late rains than the relatively Calif. p. 39-41. (Mimeo release.) few mature medusahead plants on the heavy N- Dense stands of medusahead occurred on soils with fertilized plots. loam, clay loam, or clay surface texture, with good 12 water-holding capacity. These soils had a blocky or MURPHY, A. H., and D. TURNER. 1959. A study platy structure, not granular or crumb. Soils support- on the germination of medusahead seed. Calif. Dept. ing dense stands of medusahead have a reaction of Agri. Bull. 48:6-10. ranging from calcareous to moderately acid, although Burning medusabead in the dry stage offered an most of them were slightly acid. economical method of controL Fire decreased the seed crop of this annual, thus diminishing the num- McKELL, C. M., J. MAJOR, and E. R. PERRIER. ber of plants in the next growing season. The most 1959. Annual range fertilization in relation to soil effective fire burned slowly and was directed toward moisture depletion. J. Range Manage. 12:189-193. burning downslope and against the wind. The oppo- Fertilizer treatments of 150 lbs. N per acre, 200 lbs. site of this created a fast flash fire and many seed- phosphorus per acre, and 150 lbs. nitrogen plus 200 heads were left unburned. Seed germination was lbs. phosphorus per acre were applied to an annual higher on poorly burned areas whereas little germina- grassland. Medusahead plants that received applica- tion occurred on well-burned sites. tion of nitrogen reduced the soil moisture below the field capacity (0.3 bar) earlier in the season than on MURPHY, A. H., and W. C. LUSK. 1961. Timing the phosophorus or non-fertilized plots. Combination medusahead burns to destroy more seed-save good of nitrogen and phosphorus resulted in a significant grasses. Calif. Agric. 15:6-7. interaction that gave increased yield of medusahead. Growth of summer-growing, annual weeds was con- Control of medusahead (ElymusDATE. caput-medusae) on siderably retarded by depletion of soil moisture at all rangeland is a major problem on many acres in Cal- depths where fertilizer was applied. ifornia. The purpose of burning is to destroy the seed in the head before it shatters and is deposited in the ground. In manyOF circumstances, where burning is McKELL, C. M., J .P. ROBISON, and J. MAJOR. properly accomplished, the medusahead stand will be 1962. Ecotypic variation in medusahead, an intro- substantially reduced during the next growing sea- duced annual grass. Ecology 43:686-698. son. Burning as soon as soft chess (Bromus mollis) is Medusahead seeds were collected from 13 locations in shattering seed, and while medusahead is still intact, California, Oregon, Washington, and Idaho. Signifi- favors the seed survival of soft chess during a fire. cant in percent germination, rate of root growth, plant OUTOther factors that also must be considered when burn- height, and phenology were observed. Seeds collected ing include the condition of other fuel, weather, ter- from locations with relatively low precipitation had rain, and time of day. the lowest germination percentages; seeds from loca- IS tionswith relatively high precipitation had the highestgermination.Root elongationwas more MUTCH, R. W., and C. W. PHILPOT. 1970. Rela- rapid from seed collected in Washington and Califor- tionof content to flammability ingrasses.For. nia than in Oregon. The time interval of heading be- Sci. 16:64-65. tween plants from California and Oregon was 38 Medusahead and cheatgrass were found to differ days; the seed-maturity interval between plants from greatly in total ash content. Ash contents of cheat- these two locations was 15 days. grass and medusahead were 5.04 and 18.49 percent, information:respectively, while silica-free ash contents were 0.99 McKELL, C. M., A. M. WILSON, and B. L. KAY. and 1.35 percent. Thermoanalyses indicated pyro- 1962. Effective burning of rangelands infested with lytic similarity between the two grasses. Results sug- medusahead. Weeds 10:125-131. gested the silica fraction should be discounted when Medusahead (Elymus caput-medusae L.) matures relating ash content to pyrolysis and ignition processes later in the spring than most associated species, and of wildiand fuels. has a seed head moisture content of more than 30 percent for approximately a month after and NAKAI, Y., and S. SAKAMOTO. 1977. Variation and stems begin to dry. High temperaturecurrent is more injuri- distribution of esterase isozymes in Heteranthelium ous to seed viabilityPUBLICATION when seed moisture content is and Taeniatherum of the tribe Triticaea, Gramineae. high. Control burns of medusahead infested rangeland Bot. Mag. Tokyo 90:269-276. were most effective in late afternoon when burning Esterase isozyrne variations of Heteranthelium pili- slowly (into a mild wind) and at the soft dough stage ferum, Taeniat herum asperum and T. crinitum col- of medusahead seed development. lected in Iraq, , and were analyzed by most gel isoelectric focusing. In H. piliferurn, two types of MORTON, H. L., P. J. TORELL, and R. H. HAAS. esterase zyrnogram, Hi and H2, were found. It was THIS1958. The effects of rate and date of dalapon applica- demonstrated that a pair of allelic genes, which is tion on control of medusahead rye, Elymus caput- shown in the heterozygotes, controls the difference tnedusae L. Res. Prog. Rep., WWCC. p. 25-26. between type Hi and H2. Two types of esterase RatesFor of 1.0, 2.0, and 4.0 pounds of dalapon per acre zymogram, Ti and T2, were observed in two species were applied on April 27, May 31, and June 26, 1956, of Taeniatherum. The majority of strains having type the dates corresponding to the two-leaf, late boot, Hi of H. piliferum and type Ti of T. crinitum was and dough stageshttp://extension.oregonstate.edu/catalog of growth respectively. All treat- distributed in the highly elevated plateau of the Ana- ments were applied in water equivalent to 40 gal- tolian and Iranian highlands, while strains with H2 lons per acre with a power sprayer. The 2.0 pound and T2 of these two species were found in the western rate applied on April 27, 1956, was most effective foothills of the Zagros Mountains, the Tigris basin of in controlling medusahead. Mesopotamia, and the central Anatolian plateau. 13 NELSON, J. R., and A. M. WILSON. 1969. Influence REDONDO, P. B., C .E. LUIS, M. A. PUERTO, and of age and awn removal and dormancy of medusa- J. M. COMEZ. 1974. Description of four stages in head seeds. J. Range Manage. 22:289-290. secondary succession in Sayago .Revista Pastos. 4:235-245. The effects of seed age and awn removal were stud- A typical example of secondary plant succession in a ied in two medusabead strains having different post- zone with relatively fertile soil in S. W. Zamora prov- maturity seed dormancy characteristics. Awn removal ince, Spain, is described. The study was carried out increased the percentage germination. The proximity of removed awns inhibited the germination of de- on four plots previously cultivated and abandoned for awned seeds. Dormancy of intact seeds and inhibi- (a) 2 years, (b) 5 years, (c) 10 years and (d) 20 tory effects of awns decreased with increasing age of years. Botanical composition of the four plots is given. seeds. In (a) Vuipia myuros and Broinus commutatus were dominant. In (b) Gaudinia fragiiis, Cynodon dacty- ion, Bromus commutatus, Elymus (= Taeniatherum) caput-medusae and Vuipia bromoides were dominant. The greatest differences between plots (b) and (c) NELSON, J. R., C. A. HARRIS, and C. J. COEBEL. were an increase in B. commutatus and Vicia angusti- 1970. Genetic vs. environmentally induced variation folia and decrease in V. myuros, V. bromoides, Tn- in medusahead, Taeniatherum arpert4m (Simonkai) folium campestre, T. giorneratum and other spp. In Nevski. Ecology 51:526-529. (d) Arrhenatheruzn DATE.elatius, , F. praten- The influence of seed-nursery environment on geneco- sis, G. fragilis and T. pratense were dominant. logical characteristics of 20 medusahead strains was ROBOCKER, W. C. 1973. Production potential of studied. Environmentally induced variation was ob- four winter annual grasses. J. Range Manage. 26:69- served in germination, early height development, and OF winter survivaL Small but significant variation dates 70. of spike emergence and anthesis, caused by differences In nursery trials on an individual plant basis in 1962- in seed-nursery environment, were observed. Results 4, average herbage DM yields of Bromus tectorum, B. suggest that the common practice of attaching geneco- japonicus, B. brizaeformis and Taeniatherum asperum logical significance to wild-grown seed may be sub- (= T. caput-medusae) were 6.9, 7.7, 4.9, and 3.8 ject to error, especially in germination and early OUTg/plant, respectively. The results were considered to phenological stages after germination. support the view that T. asperum in B. tectoruin IS should be selectively controlled with diuron. ROBOCKER, W. C., and R. D. SCHIRMAN. 1976. Re-seeding trials on Columbia basin rangelands dom- PARISH, R. L. 1956. A study of medusahead rye, inated by winter annual grasses. J. Range Manage. Elymus caput-medusae L., including some of the 29:492-497. morphological and physiological factors influencing its growth and distribution, and determining some pos- A series of trials was conducted north of the Snake sible methods for its control on Idaho ranges. M.S. River to determine the feasibility of establishing information:crested wheatgrass (Agropyron cnistatunz) on range- Thesis. Univ. of Idaho, Moscow. 79p. land dominated by Broinus tectorum and Taenia- Moisture requirements of medusahead rye indicate the therum asperum. Excellent control of annual grasses time precipitation occurs is of greater significance in and broad-leaved weeds was obtained with several its propagation than is the total precipitation. Seedling herbicides, atrazine at 1.1 kg/ha as a fallow treatment measurements of medusahead rye were made during before sowing being the most satisfactory. Late au- the growing season. Soils supporting dense stands of tumn or early spring sowing using a rangeland drill, medusahead had a pH range from 6.65 to 7.00. The modified to give some seedbed preparation in the row, root system of medusahead rye is shallow and is not combined with control of annual weeds, provided extensiveindevelopment.current Medusahead seedlings favorable conditions for germination and emergence emerge fromPUBLICATION soil depths up to 1 1/2 inches, if the of A. cristatuin seedlings; nevertheless, in most experi- soil surface is compact, and from a maximum of one ments they failed to establish. Trials with a soil fumi- inch in sand. Medusahead rye seed maintained over gant (methyl bromide) resulted in excellent stands of a six-month period was approximately 15 percent established plants, indicating that microbiological fac- dormant. Limited usage of chemicalsamino triazol, tors may be a primary cause of the failure of seed- IPC, and CIPCformost medusahead rye control on ings under stress. THISranges appeared practicable and possible. Dalapon gave good control at a low rate. Cultural treatments SAKAMOTO, S. 1968. Interspecific hybrid between applied in the spring did aid in the control of medu- the two species of the Taeniatherum of the saheadFor rye, especially in combination with chemical tribe . Rep. Nat. Institute of Genetics 19:39- treatments. Plowing and discing significantly reduced 40. stands. Burning in the spring did not give appreciable The genus Taeninatherunz comprises two diploid an- controLhttp://extension.oregonstate.edu/catalog Of plowed, disced, burned, and check cul- nual species (2n = 14), asperum and crinitum. A tural plots, reseeded perennial grasses became es- strainof Taeniatherum asperum was crossed re- tablished only in the plowed plots. Species showing ciprocally with a strain of Taeniatherum crinitum. some degree of success in establishment were inter- Only three F1 plants were obtained; one from Taenia- mediate wheatgrass, crested wheatgrass, and beardless therum asperum x Taeniatherum cniniturn and two wheatgrass. from the reciprocal combination. 14 SAVAGE, D. E., J. A. YOUNG, and R. A. EVANS. seed is collected while the heads still retain a green- 1969. Uti1i7tion of medusahead and downy brome ish color. Carry-over of viable seed in both litter and caryopses by chukar partridges. J. WildL Manage. soil is shown to occur for at least one year. Fire- 33:975-978. damaged seed from burned areas did not germinate Chukar partridges(Alectoris graeca)in separate in the laboratory, but substantial numbers of undam- groups were fed rations consisting of caryopses of aged seeds from the burned areas genninated readily. downy brome (Bromus tectorurn) and inedusahead (Taeniatherum asperum), and commercial game farm SWENSON, C. F., D. Le TOURNEAU, and L. C. pellets. The birds readily ingested the caryopses of ERICKSON. 1964.Silicain medusahead. Weeds both grasses. The caryopses of medusahead appeared 12:16-18. to be largely indigestible. Severe weight losses oc- Collections of plants of medusahead, Elgmus caput- curred when birds were fed caryopses of either spe- medusae L., were made from natural infestations in cies. Birds fed downy brome appeared in better con- Nez Perce County and Washington County in north- dition than those fed medusahead. ern and southern Idaho, respectively. The ash and silica content (dry weight basis) decreased as the SCHOOLER, A. B., A. R. BELL, and J. D. NALE- plant matured. The total ash of the entire plant con- WAJA. 1972. Crosses between jubatum L. tained from 72 to 89 percent silica. Similar percent- and Taeniatherum asperum (Sim.) Nevski to de- ages of silica in ash were obtained in the cuims, heads, termine genomic relationships. Crop Sci. 12:542-544. and seeds of the plant. X-rayDATE. diffraction patterns and F1 hybrids were obtained from crosses between Hor- polarizing microscope examinations showed the min- deum jubatum L. (2n=28) and Taeniatherunz as- eral form of silica to be opal. Heavy deposition of perum (Sim.) Nevski (2n = 14). The F1 hybrids had silica was found in the barbs of awns, in the epidermis a chromosome complement of 2n = 21 and were self- of the leaves, cuims,OF glumes, and seeds, and in strands sterile. Chromosome behavior was irregular in micro- beneath the epidermis. sporocytes of the hybrids examined. Chromosome doubling was induced in F1 hybrids by coichicine TORELL, P. J., L. C. ERICKSON, and R. H. HASS. treatment and partially self-fertile amphiploid inter- 1961. The medusahead problem in Idaho. Weeds generic hybrids (2n = 42) were produced. Cytological 9:124-131. observations showed many micronuelei in the micro- Medusahead,OUT Elymus caput-medusae L., is the worst spores which resulted from chromosome fragmenta- range weed in Idaho because of its rapid migration, tion during meiosis II. The F1 intergeneric hybrids its vigorous competitive nature, and its extremely low and amphiploid resembled the Hordeum parent more ISforage value. Burning, dalapon, discing, and plowing closely than Taeniatherum but were smaller than in various combinations have provided control of two either parent in most morphological characteristics. successive medusahead seed crops before seeding There was oniy slight evidence of a genome rela- desired forage species. A single burn will not remove tionship between the two genera. sucient medusahead seed to permit the successful establishment of wheatgrasses. Burning will enhance SHARP, L A., and E. W. TISDALE. 1952. Medusa- the effectiveness of tillage and herbicide treatments head, a problem on some Idaho ranges: a preliminary by removing the heavy layer of medusahead litter, by study. Forest, Wildi., and Range Exp. Sta., Univ. of information:destroying some seed, and by placing the remaining Idaho. Res. Note 3, 9 p. seed in contact with the mineral soil where they can Medusahead is an annual immigrant from Portugal be germinated and subsequently destroyed. and Spain that is becoming a serious problem on rangelands in west central Idaho. The exact time of TORELL, P. J. 1967. Dowponan aid to reseeding introduction to this country is not known, but the first medusahead-infestedrangeland.Down toEarth collection was made in 1901 near Steptoe, Washing- 23:6-8. ton, by C. R. Vasey. Estimates show approximately 30 Dowpon grass-killer applied at 3 pounds in 10 gal- thousand acres of rangeland in Idahocurrent are infested with lons of spray per acre consistently was effective in medusahead. Areas of main infestation are those with controlling medusahead. In chemical fallow, use of 10 to 20 inches ofPUBLICATION precipitation, formerly covered with Dowpon after burning controlled rnedusahead but a sagebrush-grass or bunchgrass type vegetation. cheatgrass and broadleaf weeds developed. Other Medusahead normally germinates in the fall with seed tests indicated successful control of these weeds with head formation occurring in early spring. Seeds ma- timely application of Dowpon and 2,4-D herbicides. ture in the latter part of June or first part of July. Tillage was not required to obtain establishment of Forage value of medusaheadmost is extremely low and wheatgrass seedlings. whereTHIS it is grazed by livestock some mechanical in- jury has been reported. A cover of medusahead is TORELL, P. J., and L. C. ERICKSON. 1967. Re- beneficial in preventing soil erosion. Litter accumula- seeding medusahead-infested ranges. Univ. of Idaho, tions in Formedusahead stands add to the organic matter Agr. Exp. Sta., College of Agr. Bull. 489. 17 p. of the soil. Investigations in the revegetation of medusahead- infested ranges in southwestern Idaho revealed two SHARP, L. A.,http://extension.oregonstate.edu/catalog M. HIRONAKA, and E. W. TIS- essential factors: (1) Control of annual weed species DALE. 1957.Viability of medusahead seed col- is necessary, for the competing vegetation is a com- lected inIdaho.J.Range Manage.10:123-126. plex of annual weeds rather than medusahead alone Medusahead produced a large amount of seed an- (2) two successive crops of annual weeds should be nually, and fairly high viability is attained even when treated before seed formation to reduce weed seed 15 reserve, enhancing survival of wheatgrass seedlings. TURNER, R. B. 1965. Medusahead control and man- Under certain experimental conditions, these require- agement studies in Oregon. p. 70-73. IN: Proc. of ments were satisfied by each of the following dual the Cheatgrass Symposium, Vale, Oregon. (Portland) treatment schedules: tillage plus tillage, tillage plus Bureau of Land Management. herbicide, burning plus tillage, and burning plus On sites containing medusahead which are suitable herbicide. The effective treatments included at least for tillage, control of the weed and replacement by one tillage operation. The most desirable herbicide perennial type seeded forage are easily attainable. treatment was dalapon followed by 2,4-D. Burning Conversely, on sites which are shallow, steep or was particularly desirable as the first of a dual treat- rocky, with an inherently low forage potential, the ment schedule. The most important benefit from problem of medusahead replacement has no im- burning was removal of the dense mantle of medusa- mediate solution by conventional means. Atrazine head litter that impedes tillage, lowers the effective- and bromacil (Hyvar-x by duPont's label), both soil ness of herbicides, and prevents preparing a quality sterilants, have been effective in controlling medusa- seedhed. Although the dual weed control treatments head and cheatgrass at rates of 1 pound per acre reduced the annuaal weed populations, a largequan- (active material) applied in late fall and 1/2 pound tity of dormant weed seed remained in the soil. An per acre applied in early spring or fall, respectively. application of atrazine showed promise for overcom- IPC (4 pounds per acre) plus 2,4-D (3/4 pounds ing this difficulty. Because of high seed vigor, Nordan per acre), applied in late fall or winter, has given crested wheatgrass is the most desirable grass for re- adequate control ofDATE. rnedusahead and cheatgrass. seeding medusahead infested ranges in southwestern Crested wheatgrass germination has been attained by Idaho. drill seeding in the spring after application. Paraquat, a herbicide reported to give good annual grass control, has given veryOF poor medusahead control under eastern 61. TURNER, R. B., C. E. POULTON, and W. L. Oregon conditions. Medusahead vigor actually was GOULD. 1963. Medusaheada threat to Oregon increased from this herbicide. Comparative medusa- rangeland. Oregon State Univ., Agr. Exp. Sta., Spec. head clippings following 35 lbs/acre of nitrogen Rep. 149. 22 p. showed that cattle relished the fertilized plots. Medusahead is one of the primaiy range weed prob- OUTTURNER, R. B. 1969. Vegetation changes of com- lems in Oregon. Estimates indicate medusahead oc- munities containing medusahead (Taeniatherum as- curs throughout an area in excess of 2 million acres perum (Sim.) Nevski) following herbicide, grazing, in Oregon. In Oregon, medusahead has been grow-IS and mowing treatments. Ph.D. Thesis. Corvallis, Ore- ing within a mean annual precipitation range of 11 to gon State University. 199 p. 40 inches. Generally, the weed has been observed on clay barns and heavy clays which havea high water- Although high variations resulted among herbicide holding capacity. Since medusahead matures two to treatments, frequencies of cheatgrass (Bromus tec- three weeks later than cheatgrass (Bromus tectorum torurn) and medusahead were reduced after applica- L.), the ecological amplitude of cheatgrass may ex- tions of atrazine (2 lb/acre) and isocil (1 lb/acre). tend beyond that of medusahead into areas of progres- Vigor of bluebunch wheatgrass (Agropyron spica- sively drier climate. The low palatability of medusa-information:turn) increased markedly from the reduction in an- head and mechanical injury to grazing animalsre- nual plant competition. A rate of 1 1/2 lb/acre of sulting from the long, barbed awus and sharp seeds atrazine substantially reduced the frequency of Sand- greatly reduce livestock grazing capacity of range- berg's bluegrass (). The response of lands. The accumulation of slowly decomposing litter sheep to two ecological sites was clearly evident. considerably safeguards the loss of soil by wind and Complete utilizationof inedusahead was readily water erosion in areas that are overgrazed and sus- attained by grazing in a late grazed mesic , but ceptible to erosion. Practices which offer some degree highly ineffective even with more sheep days grazed of control include tillage, seeding,current burning, application on a xeric pasture. California oatgrass (Danthonia of herbicides,PUBLICATION and grazing management. Range seed- californica)plants were weakened considerably by ing, when properly combined with other practices competition from medusahead. Marked increase in such as tillage, burning, or use of herbicides, seems vigor resulted for this perennial grass in the early-late to be the most positive and sure control of medusa- mowed treatment. It was concluded that rapid im- head. Results of burning trials have been highly provement should be possible providing medusa- variable; and,most used alone, satisfactory results cannot head was removed by grazing management and late be attained. Results from studies in eastern Oregon mowing on all but two of the stands studied. THISindicate dalapon and atrazine give adequate control of medusahead at rates of 2 pounds of active chemical VAN DYNE, C. M. 1962. Micro-methods of nutritive per acre. Although numerous reports have indicated evaluation of range forages. J. Range Manage. 15:303- thatFor medusahead is unpalatable to all classes of live- 314. stock, other investigators have found that heavygraz- Results of preliminary studies concerning the develop- ing in spring resulted in a thinned stand of medusa- ment and modification of techniques for in vitro and head; whereas,http://extension.oregonstate.edu/catalog light or no grazing resulted ina dense in vivo nutritive evaluation of range plants were stand. Range fertilization, especially with nitrogen, discussed. Several types of forage samples and cel- offers a possible means of improving the palatability lulose sources were used. Immature medusahead wild of medusahead to encourage its use by grazing ani- rye generally had the highest cellulose digestion mals. values of all forages at different times of digestion. 16 Cellulose digestion of mature medusahead wildiye In one series of testing in the greenhouse, siduron was similar to that of the mature mixed annual range controlled seedlings of downy brome and medusahead forage for fermentations of greater than 24 hours. but did not harm seedlings of either crested or inter- mediate wheatgrass. WILSON, A. M., D. E. WONDERCHECK, and C.J. GOEBEL. 1974. Responses of range grass YOUNG, J. A., R. A. EVANS, and R. E. ECKERT, seeds to winter environments.J. Range Manage. JR.1969. Emergence of medusahead and other 27: 120-122. grasses from four seeding depths. Weed Sd. 17:376- Grass seeds enclosed incotton-screen bags were 379. placed 2.5 cm deep in soil in the field in November, Emergence of 23 medusahead (Taeniatherum as- January, or March and tested for germination at 10 peruin (Sim.) Nevski) selections from four seeding degrees C in the laboratory at frequent intervals. In depths in two soils were investigated and compared general, the number of days to 25 percent germina- with that of other grasses. Increased depth markedly tion decreased with increasing exposure in the field. reduced total emergence of medusahead and vari- After one month of exposure, the order of species in ability among selections. Selections of intermediate decreasing germination rate was Bromus tectorum, wheatgrass (Agropgron intermedium. (Host) Beauv) Taeniatherum asperum(=T.caput-medusae), and pubescent wheatgrass (Agropyron trichophorum Agropyron desertorum, A. sibiricum, A. spicatum, and (Link) Richt.) and downy brome (Bromus tectorum B. inermi.s. The order of seedling emergence was the L.), among other grasses, DATE.greatly exceeded medusa- same except that T. caput-medusae emerged before head in emergence from all depths. Standard crested B. tectorum. It was concluded that seeds might be wheatgrass (Agropyron desertorum (Fisch. ex Link) safely sown in winter or very early spring on ranges Schult.) had less emergence than medusahead from at low altitudes in the Northwest. all depths. TheOF 3- and 4-inch planting depths ex- ceeded the coleoptile length of medusahead. When YOUNG, J. A., R. A. EVANS, and R. E. ECKERT, medusahead emerged from these depths, the first JR. 1968. Germination of medusahead in response true leaf was recurved and chlorotic. to temperature and afterripening. Weed Sci. 16:92-95. Requirements for germination of 23 medusahead YOUNG, J. A., R. A. EVANS, and R. E. ECKERT, (Taeinatherum asperuin (Sim.)Nevski) selections JR.OUT 1969. Wheatgrass establishment with tillage and were investigated in relation to temperature and herbicides in a mesic medusahead community. J. afterripening requirements, and were compared with Range Manage. 22:151-155. thegerminationcharacteristicsofothergrasses. IS Intermediate wheatgrass seedlings were successfully Medusahead germinated best at 10 to 15 C. Germina- established in a medusahead community in 1965, tion percentages were markedly lower at 20 and 25 C. 1966, and 1967 with mechanical or chemical-fallow Unlike medusahead, germination of all competing or treatments. Summer fallowing by disc harrowing was replacement species tested was markedly decreased the most successful treatment. The most productive at lower temperatures (10 C). Above 15 C, medusa- wheatgrass stands suppressed but did not eliminate head selections had strong afterripening requirements medusahead. which decreased over time. Shortly after maturity, medusahead caryopses germinated only at low tem-information:YOUNG, J. A., and R. A. EVANS. 1970. Invasion of peratures (10 and 15 C). Germination temperatures medusaheadintotheGreatBasin.WeedSci. became less dominant after a 180-day afterripening 18:89-97. period. Characterization of soil and vegetation assemblages, many of which are infested with medusahead (Taeni- YOUNG, J. A., R. A. EVANS,and R. E. ECKERT JR. atherum asperum (Sim.) Nevski), on the margin of 1968. Germination of medusahead in response toos- the Great Basin was investigated. Interpretations of motic stress. Weed Sci. 16:364-368. these assemblages provided an index of the validity Requirements for germination currentand rate of juvenile of the basic environmental unit of this ecosystem root and shoot PUBLICATIONelongation of 23 medusahead (Taeni- which can be manipulated through weed control and atherum asperurn (Sim.) Nevski) selections were in- revegetation techniques. Vertisol (churning clay soils) vestigated in relation to osmotic stress. These were sites with sparse native plant communities were more compared with the germination and elongation char- susceptible to medusahead invasion than more com- acteristics of other grasses. Aqueous solutions of dif- plex low sagebrush (Artemisia arbuscula Nutt.) or ferent osmotic pressuresmost were obtained by dissolving low sagebrush-woodland communities on related clay polyethylene glycol in water. Successive 4-bar in- soils.If the more complex communities were de- THIScreases in osmotic pressure markedly reduced medusa- graded to a low seral state, medusahead can invade head germination until germination terminated at and occupy the site. Wet meadows and burned conif- 16 bars. Other grass species exhibited higher germina- erous forest sites at high elevations were the only tion thanFor medusahead under osmotic stress. Medusa- sites where medusahead occurred on soils with tex- head juvenile root and shoot elongation under low turesother than clay.Big sagebrush(Artemisia and moderate osmotic pressure exceeded all other tridentata Nutt.) communities on medium to coarse species tested.http://extension.oregonstate.edu/catalogtextured soils were very resistant to medusahead in- vasion. The restriction of medusahead to certain YOUNG, J. A., R. A. EVANS, and R. E. ECKERT sites controls the mechanism of invasion and interacts JR. 1969. Population dynamics of downy brome. with the breeding system of the species to influence Weed Sci. 17:20-26. its evolution. 17 YOUNG,. J. A., R. A. EVANS, and B. L. KAY. 1970. YOUNG, J. A., R. A. EVANS, and B. L. KAY. 1971. Phenology of reproduction of medusahead, Taeni- Response of medusahead to paraquat. J. Range Man- atherum asperum. Weed Sci 18:451-454. age. 24:41-43. The phenology of reproduction was highly variable Medusahead plants from 23sources weresus- among 23 selections of medusahead (Taeniatherum ceptible to paraquat at Davis, California, but re- asperum (Sim.) Nevski). Selections with markedly sistant to applications of this herbicide at Reno and early and late maturity were observed. Phenology Stead, Nevada. Differences in response were not be- generally was consistent during four years of testing cause of ecotypic variability among the sources. The at Reno, Nevada, and during two years at Davis, Cali- differencesinsusceptibility between thecis and fornia.Individualselectionsdifferedgreatlyin transmontane populations apparently were because phenology between two locations. Some of the selec- of differences in unidentified characteristics of the tions exhibited phenotypic plasticity in phenology two environments. when grown in competition with other weeds. YOUNG, J. A., R. A. EVANS, and B. L. KAY. 1971. YOUNG, J. A., and R. A. EVANS. 1970. Weed con- Germination of caryopses of annual grasses in simu- trol in wheatgrass seedbeds with siduron and picloram. lated litter. Agron. J. 63:551-555. Weed Sci. 18:546-549. A technique was developed for germinating grass Pre-emergence applications of 3 lb/A of 1- (2-methyl- caryopses in simulated litter, without the base of the cyclohexyl) -8-phenylurea (siduron) plus 0.3 lb/A of caryopses in contact withDATE. a liquid moisture-supplying 4-amino-3,5,6-trichloropicolinic acid (picloram) sue- substrate. Litter germination of five annual species of ciently suppressed competition from downy brome bromegrass and medusahead differed markedly in (Bromus tectorum L.) or medusahead (Taeniatherum response to temperature from 10 to 25 C, compared asperum (Sim.) Nevski) and associated broadleaf to germinationOF of the same species in petri dishes. species to allow marginal establishment of intermedi- The species also differed in their rates of root elonga- ate wheatgrass(Agropyron intermediuin(Host.) tion and root persistence under repeated drying cycles Beauv., var. Amur) seedlings. The technique was at incubation temperatures from 10 to 25 C. The only successful on semi-arid range sites with above- differences in litter germination among annual grasses average soil moisture and moderately dense stands investigated may be the basis for dominance of one of weed grasses. The range in tolerance of the three OUTspeciesover another under specifictemperature species to siduron is very similar, but downy brome regimes. isslightly more susceptible than medusahead or intermediate wheatgrass. There is a significant nega-IS YOUNG, J. A., and R. A. EVANS. 1972. Conversion tive relation between plant moisture stress and root of medusahead to downy brome communities with length of intermediate wheatgrass plants when root diuron. J. Range Manage. 25:40-43. elongation is suppressed by low rates of siduron. Application of diuron at 2 lb/acre changed plant communities from medusahead to downy brome YOUNG, J. A., and R. A. EVANS. 1971. Medusa- dominance. This conversion lasted for at least three head invasion as influenced by herbicides and grazing years and greatly increased utilizable forage. on low sagebrush sites. J. Range Manage. 24:451-454. Responses of vegetation after herbicide applicationsinformation:YOUNG, J. A., R. A. EVANS, and J. ROBINSON. and grazing were observed in the low sagebrush com- 1972. Influence of repeated annual burning on a munity. Removal of the shrub cover with 2,4-D did medusahead community. J. Range Manage. 25:372- not necessarily lead to an increase in medusahead 375. because the perennial grasses quickly made use of Three one-acre blocks were burned three consecutive the released environmental potential. Spraying 2,4-D years. An increase of medusahead and decrease in for brush control combined with application of atra- downy brome were observed. Changes in densities zine for herbaceous weed control further increased of annual grasses from burning were not a result of perennial grasses when not grazed. However, when destroying the caryopses, but probably were caused grazed, medusahead greatly currentincreased at the expense by alteration of the seedbed environment. No changes of perennialPUBLICATION grasses within three years following were observed in perennial grass populations in rela- treatment. tion to burning. most THIS For http://extension.oregonstate.edu/catalog

18