Control and Treatment

Lana Vetch for Medusahead Control

Robert S. Mac Lauchlan, Harold W. Miller and Oswald K. Hoglund. 1970. J. Range Manage. Vol. 23; 5, pp. 351-353.
Location: California and Southwestern Oregon (The Pleasanton Plant Materials Center)
The annual legume Lana vetch, an improved variety of woollypod vetch, was shown to control for the invasion of medusahead. Studies on the use of Lana vetch for medusahead control show that, where Lana vetch is adapted, overseeding, annual fertilization with phosphate and sulfur, and deferred grazing are key to its suppression of medusahead.  Yet, Lana vetch can also be successfully established from direct seeding without seedbed preparation, making it a a practical method of controlling medusahead on rangeland that is too rough or steep to permit mechanical seedbed preparation. These studies suggest that increased production and improved quality of forage from medusahead infested annual grass ranges are the result of planting Lana vetch.

Effective Burning of Rangelands Infested with Medusahead.
Cyrus M. McKell, Alma M. Wilson and B. L. Kay. 1962. Weeds: 10; 2, pp. 125-13.
Location: Solano County, California
Lab and Field studies showed factors necessary for effective control burns of medusahead-infested rangeland .
1. The viability of medusahead seed (prior to germination) was reduced only when exposed to temps of 392 degrees F. for at least 90 seconds.
2. High seed moisture content and exposure to high temperature (392 degrees F) reduced medusahead and soft chess seed germinability to about zero.  This interaction may prove important in timing field burning operations.
3. Moisture content of medusahead seeds remained above 30 % for approximately a month after leaves and stems and associated vegetation had dried, and seed heads had higher moisture content than medusahead litter in the early morning of a typical summer day in the California Central Valley.
4. These studies suggest that the most effective control of medusahead with burning occurred in late afternoon when fires burned slowly (into a mild wind) and at the soft-dough stage of medusahead seed development.

Potential for Biological Control of Downy Brome (Bromus tectorum) and Medusahead (Taeniatherum caput-medusae) with Crown and Root Rot Fungi.
William E. Grey, Paul C. Quimby, Jr., Donald E. Mathre and James A. Young. 1995.Weed Technology 9:2, pp. 362-365.
Location: Montana
The effects of five soil fungi were evaluated for disease reaction, root dry weights and shoot dry weights on five grass species; downy brome, medusahead, squirreltail, western wheatgrass, and winter wheat.
Methods: The fungal pathogens used in the experiments are endemic to Montana agricultural soils and were isolated from diseased roots and crowns of wheat or barley. The fungi used in the experiments included: barepatch (Rhizoctoniasolani Kuhn); browning root rot (Pythium ultimum); common root rot (Cochliobolus  sativus); crown rot (Fusarium culmorum); and take-all (Gaeumannomyces graminis). Fungi was applied to plants through an inoculationprocess.
Disease evaluation: The roots of plants for each grass were washed free of soil and visually evaluated for the extent of root discoloration. Disease reaction was measured on a percentage of 0 = healthy roots to 100 = plant death. Plant growth responses to infection were assessed based on the root dry weight including crown and root tissues and on the shoot dry weight including above-ground foliage. Tissue pieces (I cm) were excised from diseased roots and placed on potato( Solanum tuberosum L .) dextrosem edium (pH 6) to isolate and identify the causal fungus.
Results for Medusahead: Medusahead was susceptible to crown rot and take-all but not to barepatch, browning root rot, and common root rot as compared to the control. Root dry weight of medusa-head was not reduced by the diseases, but take-all significantly reduced the shoot dry weight.
Take-all is associated with plants growing in high soil moisture and resulted in susceptible disease reactions on all grasses tested, including downy brome and medusahead.  Downy brome and medusahead were also susceptible to crown rot, which causes greatest damage on moisture stressed plants.  Thus, crown rot may be a potential biological control of these grassy weeds because of its adaptability to the arid regions of the western U.S. and its low impact on a desirable grass, such as western wheatgrass.

Revegetation of Medusahead-Invaded Sagebrush Steppe
Kirk Davies. 2010. Rangeland Ecol. & Manage 63:564–571
Study Location: Oregon
Objective: Most efforts to re-vegetate medusahead-infested plant communities are unsuccessful because perennial bunchgrasses rarely establish after medusahead control. To determine the effects of prescribed burning (spring or fall), fall imazapic application, and their combinations were evaluated for medusahead control and the establishment of seeded large perennial bunchgrasses.
Methods: One growing season after burning and application of imazapic, desert wheatgrass and squirreltail seed were drilled into treatment plots. Vegetation characteristics were measured the second and third year after seeding.
  • Medusahead was best controlled by prescribed burning and then treated with imazapic.
  • The prescribed burned followed by imazapic application had greater cover (10 times) and density (8 times) perennial bunchgrass than untreated areas.
  • Prescribed burning, regardless of season (spring or fall), was not effective at controlling medusahead or promoting establishment of perennial bunchgrasses.
  • The results of this study question the long-term effectiveness of using imazapic in re-vegetation efforts of medusahead-infested sagebrush steppe without first prescribed burning the infestation.
  • Effective control of medusahead appears to be needed for establishment of seeded perennial bunchgrasses.

Medusahead Control with Fall- and Spring-Applied Herbicides on Northern Utah Foothills
Tom Monaco, Travis Osmond, and Steve Dewey. 2005. Weed Technology 19:653–658
Location: Avon, UT
Objective 1: To determine the effect of prescribed burns on low- and high-litter sites in northern Utah prior to conducting experiments.
Results: Large differences in pretreatment medusahead litter between the sites resulted in less surface area burning at the low-litter site (10%) compared to the high-litter site (80%). Thus, after burning the high litter site contained less litter than low-litter site.
Objective 2: To evaluate the effects of fall and spring applications of sulfometuron at 39 or 79 g ai/ha and imazapic at 70 or 140 g ai/ha on medusahead, perennial grasses, annual and perennial forbs, and bare ground cover.
Methods: Plots were 3 x 49 m. Herbicides were applied using either an ATV-mounted, five-nozzle boom sprayer, equipped with flat-fan nozzle tips or a CO2 backpack sprayer with a six-nozzle hand-held boom equipped with flat-fan nozzle tips at high-litter sites.
  • Higher herbicide rates increased medusahead control and bare ground.
  • Herbicides were more effective when sprayed in fall vs. spring in 2001, but season did not affected medusahead abundance in 2002.
  • Oust controlled medusahead better than Plateau when sprayed in fall than spring.
  • Control was greater at the high- than low-litter site for all spring applications.
  • The high-rate, spring-applied Plateau had nearly twofold greater control than any other treatment combination.
  • Oust more effectively controlled medusahead better than Plateau at the low-litter site, for fall applications, and at both the low and high application rate.
  • The low- and high-litter sites did not differ in perennial grass cover 2 years after treatment.
  • Annual forb cover was greater, but perennial forb cover was lower at the low-litter site compared to the high-litter site.
  • Several treatment combinations maintained greater than 50% medusahead control two years after herbicide applications.
Medusahead Control
Medium (54%)
Low (29%)
High (68%)
High (57%)
High (91%)
Medium (48%)
Low (32%)
Medium-Low (38%)
Medium (56%)
Low (33%)
High (66%)
Medium (53%)
Mean percentage control of medusahead at the low- and high-litter sites in 2002. Data are displayed to interpret the herbicide-by-season-by-rate-by-site interaction.
Medusahead Control
Low Litter
High Litter
Low (40%)
Low (19%)
Low (24%)
Low (48%)
Medium (56%)
Low (20%)
Medium (55%)
Medium (56%)
Low (26%)
Low (35%)
Low (37%)
Low (41%)
Medium (53%)
Medium (54%)
Low (45%)
High (90%)

Response of Bluebunch Wheatgrass and Medusahead to Defoliation
Roger L. Sheley and Tony J. Svejcar. 2009. Rangeland Ecol. Manage 62:278–283
Location: Oregon
Objective: Our objective was to determine the short-term response of bluebunch wheatgrass and medusahead to defoliation of wheatgrass designed to stimulate regrowth through tillering. We thought clipping bluebunch wheatgrass by 20% at the 3 to 3.5 leaf stage followed by a 50% defoliation at peak standing crop would 1) increase its tillering and biomass production of bluebunch wheatgrass and 2) reduce density and biomass of medusahead.
Methods: Treatments included four initial medusahead densities (200, 333, 444, 600 plants per sq yd) created by hand-pulling and three levels of clipping. In 2006 and 2007, bluebunch wheatgrass was hand-clipped 1) by 50% once at peak standing crop (late June); 2) by 20% at the 3 to 3.5 leaf stage, then again to 50% at peak standing crop (mid May, late June); or 3) plants were not clipped. Density was sampled in 2006 and 2007, and biomass was harvested only at Star Mountain in 2007 because Warm Springs was burned by wildfire before final 2007 data could be collected.
  • In 2006, clipping and density of medusahead did not altered the number of tillers produced by bluebunch wheatgrass.
  • In 2007, clipping and density of medusahead did not affect bluebunch wheatgrass density or biomass at Star Mountain.
  • Medusahead density did not change in 2006, but increased in density and biomass in 2007 at Star Mountain in plots that were clipped twice.
  • Grazing bluebunch wheatgrass twice in the same year is a poor management practice on arid rangelands in the western US and may possibly increase the risk of annual grass invasion.

Medusahead Invasion as Influenced by Herbicides and Grazing on Low Sagebrush Sites
James Young and Raymond Evans. 1971. Journal of Range Management 24:451-454
Spraying 2,4-D for brush control combined with application of atrazine for herbaceous weed control further increased perennial grasses when not grazed, but with grazing, medusahead greatly increased at the expense of perennial grasses 3 years after treatment.
Applications of 1 lb/acre of atrazine eliminated all annual vegetation the year following application. On heavily grazed plots treated with 2,4-D and atrazine, there was severe injury to the native perennial grasses followed by an increase of medusahead.
In contrast, on non-grazed plots, the atrazine treatment increased perennial grasses, with only an occasional medusahead plant present.
This study confirms that a stable perennial grass/low sagebrush community is an effective barrier against medusahead invasion.

Medusahead (Taeniatherum asperum Nevski): A Review and Annotated Bibliography
Thomas 0. Hilken and Richard F. Miller. 1980. Agricultural Experiment Station. Oregon State University Station Bulletin 644.
Location: Oregon
Provides good information on Medusahead, with specific attention given to treatments and their effectiveness reported in literature.