Medusahead (Taeniatherum caput-medusae) is an invasive noxious annual grass of Eurasian origin that has infested 5 million acres of rangeland in California and millions more in other western states. Severe medusahead infestations result in a loss of $20/acre/year in grazing value, reduced recreational value, and extremely low biodiversity. Medusahead threatens the ecological and economic integrity of rangeland ranching, one of the major industries of California. Recent research at the University of California at Davis has demonstrated that properly timed high-density grazing can effectively control medusahead. Common methods used to achieve high density grazing include fencing, herding and attractants. The purpose of this project is to test the use of molasses sprayed on medusahead as an attractant to increase the forage utilization by sheep. In late-April of 2006 we sprayed 100 ft2 plots of medusahead with one of three different concentrations of molasses. The percent cover of individual plant species and forage biomass was monitored before and after the molasses application. The monitoring data indicated that all concentrations of molasses did not result in greater forage utilization than the control, or untreated areas. After this disappointing result, we decided to try a different approach by first training the sheep to seek molasses. In April 2008, we used a training method developed by Kathy Voth with the BEHAVE program at Utah State University to train the sheep to be attracted to molasses. We then sprayed medusahead infested areas of a rangeland grazed by the trained sheep. Once again the molasses treatment failed to attract the sheep to consume the medusahead.
Medusahead (Taeniatherum caput-medusae), an invasive noxious grass native to Eurasia, infests an estimated 5 million acres in northern California. Pellant and Hall (1994) determined that 3.3 million ac of BLM lands were cheatgrass or medusahead monocultures; nearly 14 million acres were infested with one or both; and an additional 62 million were at risk of invasion. Medusahead is perhaps the only grass that invades cheatgrass stands (Young and Evan 1970), partly due to its ability to germinate early and grow roots under cold temperatures earlier and deeper than cheatgrass and native perennials (Hironaka 1961, Harris 1977).
By 1999 medusahead was distributed over 5 million acres in northeastern CA (Miller et al. 1999). It first invaded Glenn and Colusa counties in the 1950’s. Although Young (1994) reported that medusahead had probably already invaded all suitable sites in CA, it has continued to expand steadily. Producers and Farm Advisors in Monterey and San Luis Obispo counties report that medusahead is a recent and major problem in their rangelands (R. Larsen, personal communication).
Medusahead is high in silica, unpalatable to livestock and wildlife, and slow to decompose. This results in heavy accumulation of a thatch that effectively inhibits other species and leads to a near monoculture. Once medusahead matures, it is rejected by grazing animals, birds and rodents, rendering pastures useless for livestock and wildlife. This translates into a permanent 75% loss in livestock carrying capacity (George 1992), equivalent to a loss of $20/acre/year.
The beef and sheep industry of California produced cash receipts for $1.6 billion or 22.9% of all livestock and dairy in 2003 (California Agricultural Statistics 2003). Most of the beef and sheep production in the state depends on the calf and lamb crops that are produced on rangelands and pasture. Rangelands of California are the primary forage source for the cow-calf operations that supply calves and yearlings to feedlots in California and other states. Cattle ranches are predominantly family-run cow-calf operations (Anderson et al. 2002). Thus, medusahead threatens the ecological and economic integrity of rangeland ranching, a major industry already under threat due to the demography of ranching families, and the competition from alternative, high-dollar value uses of land such as development and vineyards.
In a survey of ranchers in Solano, Yolo and Napa counties, intensive grazing was identified as the most favorable method of controlling noxious weeds (Doran 2002). Burning, herbicides and mowing are also methods used to control medusahead and other noxious weeds, but these methods were identified as less favorable by ranchers because of their difficulty, high cost, and impracticality of use in rangeland systems. Intensive grazing is viewed more favorably by ranchers for several reasons listed below:
-Intensive grazing does not require expensive external inputs since ranchers already have livestock for grazing.
-Ranchers are familiar with intensive grazing practices.
-Intensive grazing is more feasible than other weed control methods on extensive rangelands with variable topography and vegetation.
-Intensive grazing does not require special permits.
-Intensive grazing utilizes forage that would otherwise be lost if burned or killed with herbicide.
-Intensive grazing can be incorporated into the normal herd management and rotations.
In response to the survey and growing state-wide interest in controlling medusahead, a research mission was established by campus and county-based UC researchers to address the use of intensive grazing for controlling medusahead. Research has since shown that properly timed high density grazing can provide over 90% control of medusahead. Our research is now focusing on the mechanics of applying high density grazing on actual range situations through practical and feasible livestock management practices.
Anderson, M.A., S.C. Blank, T. LaMendola and R.J. Sexton. 2002. California’s cattle and beef industry at the crossroads. California Agriculture, 56(5):152-156.
Doran, M.P. 2002 Survey results. ANR-UCCE Solano, Yolo & Napa Counties. Local Fodder July 2002.
George, M.R. 1992. Ecology and management of medusahead. Department of Agronomy and Range Science. Agricultural Experiment Station. University of California, Davis, Range Science Report: 1-3.
Hironaka, M. 1961. The relative rate of root development of cheatgrass and medusahead. Journal of Range Management, 14(5):463-467.
Miller, H.C., D.W. Clausnitzer, and M.M. Borman. 1999. Medusahead. In R.L. Sheley and J.K. Petroff, editors. Biology and Management of Noxious Weeds. Oregon State University Press, Corvallis, Oregon.
Pellant, M. and C. Hall. 1994 Distribution of two exotic grasses on Intermountain rangelands: status in 1992. In: Monsen, Stephen B.; Kitchen, Stanley G., compilers. Proceedings – ecology and management of annual rangelands; 1992 May 18-22; Boise, ID. Gen. Tech. Rep. INT-GTR-313. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 109-112.
Young, J.A. and R.A. Evans. 1970. Invasion of medusahead into the Great Basin. Weed Science, 19:89-97.
Young, J.A. 1994. Ecology and Management of Medusahead (Taeniatherum- Caput-Medusae Ssp Asperum [Simk] Melderis). Great Basin Naturalist 52:245-252.
The objectives of this project are to test the effectiveness of three different concentrations of molasses in attracting sheep to consume medusahead and extend the results of the trial to local livestock producers and rangeland managers. Four treatments consisted of the following molasses concentrations and applications:
1. Control; 100% water applied at 50 gallons/acre
2. 12.5% molasses, 87.5% water applied at 50 gallons/acre
3. 25% molasses, 75% water applied at 50 gallons/acre
4. 50% molasses, 50% water applied at 50 gallons/acre
We hypothesized that the impact of sheep on medusahead would be greater than in the control plots and would increase as the molasses concentration increased.
The project was conducted on a rangeland site heavily infested with medusahead and located approximately five miles west of Davis, California. Each treatment plot (~20 feet square) was marked with heavy wood stakes and with approximately 50 feet separating plots within each block. Blocks were widely distributed across the property to ensure that the impacts on blocks were independent. The molasses treatments were applied in early-May, which was when approximately 80% of medusahead plants were in the boot stage. Approximately 100 sheep were allowed to graze the property as they normally have, with no manipulations of their concentrations in the treatment areas.
Herbage botanical composition and mass were measured prior to the molasses application and thereafter at 2, 4 and 14 days post treatment. Botanical composition by species was assessed visually (Bonham 1989) from 1 m2 quadrats in three locations in each plot. Herbage mass was evaluated by using a pressure plate in a double sampling scheme (Laca et al. 1989). Forage utilization or offtake by the sheep was determined as the difference between the before and after herbage mass measurements.
Differences between the treatments was analyzed for each response with a one-way ANOVA model.
Bonham, C.D. 1989. Measurements for Terrestrial Vegetation. John Wiley & Sons, New York, NY.
Laca, E.A., M.W. Demment, J. Winckel and J.G. Kie. 1989. Comparison of weigh estimate and rising-plate meter methods to measure herbage mass of a mountain meadow. Journal of Range Management, 42(1):71.
Our observations and the data demonstrate that the sheep impact for each molasses treatment was not different from the control treatment, with respect to both botanical composition and biomass, and was not successful in controlling medusahead. With these results we speculated that the sheep may require training in order for them to be attracted to the forage sprayed with molasses. We decided to re-test the molasses treatments after conducting a training process designed to teach the sheep to enjoy and seek feeds and forages sprayed with molasses.
In January 2007 Jim Yeager and Morgan Doran attended an information meeting titled “We’d Eat It” organized by Kathy Voth, who formally worked with Dr. Fred Provenza and the BEHAVE program at Utah State University. The meeting provided information and techniques on how to train livestock to consume specific plants, such as distaff and Italian thistle. The ten-day training process involves feeding the livestock nutritious grains with molasses on one day and without molasses on the following day. After several days of alternating different grains, the target plants are harvested and offered first with molasses, then without molasses the following day. Over the training period, the livestock learn that the offered feeds are nutritiously satisfying and consume each commodity or plant without hesitation. The livestock are then released into the weed infested pasture and seek the target weed that they learned to consume during the training process.
In October 2007, we employed the same training process over a 12-day period with 25 sheep, ending the training by offering dry medusahead residue sprayed with molasses, then without molasses. The sheep readily consumed the all the residue, which was of very poor nutritional quality. The next day we sprayed a patch of medusahead residue in the field, which the sheep readily consumed, even when they were offered alfalfa hay in an adjacent corral. The success of the training process was compelling enough for us to plan to use this technique again in spring 2008 so that we can re-test the molasses treatments for controlling medusahead.
In April 2008 we used the same training method on a different group of 20 sheep. Over a period of 12 days the sheep were exposed to five grains and two types of forage hay, each offered for two consecutive days first without molasses and then with molasses. By late April the medusahead was in a phenological stage when it is most susceptible to intensive grazing. On April 30 we sprayed three 288 ft2 plots (12 feet x 24 feet) located in 5.5 acre field. The trained sheep were confined to the field for approximately one week. Activity by the sheep in the treated plots was monitored throughout the day, and no activity in the plots was observed. We speculate that although the sheep were trained to like molasses, the attractant was not strong enough to overcome other available feed in the field that the sheep found more desirable. Some ranchers in California have successfully attracted livestock to medusahead with molasses, but only during the summer and fall months when all rangeland forage in California is typically dry and of low quality. We experienced similar behavior in the October 2007 training exercise. Unfortunately, livestock impacts on medusahead during the summer and fall months will not provide effective control.
We expect that the successful control of medusahead on rangelands with intensive grazing will produce multiple benefits for ranchers, rangeland managers and the general society throughout the Western region. Using intensive grazing for weed control reduces the use and dependency on herbicides that will kill target and non-target plants and increase the risk of impairing water quality. Rangelands can be restored to systems with higher plant species diversity, and higher forage value, thus increasing the overall value for livestock, wildlife, ranchers and recreationists. Additionally, ranchers will enhance the profitability of their operation by taking advantage of skills and materials they have already acquired through everyday ranching activities and educational workshops.
At this point in the project, we have learned that spraying molasses on medusahead to concentrate grazing is not an effective method to control medusahead. Although this conclusion is different from our expectation, we can confidently convey this message to livestock producers.
Educational & Outreach Activities
This project intentionally complements another current medusahead research control project funded by Western SARE titled “Grazing Strategies to Control Medusahead in California,” of which a major component is being conducted on the same property in Davis, CA. Because of their complementary qualities and common location, we are conducting joint field days to communicate project findings. On July 20, 2007, we conducted a field day at the project site for approximately 25 livestock producers, Cooperative Extension farm advisors and agency personnel to share information from both grazing projects and to solicit recommendations from participants. On October 15, 2008 we held another field day for visiting livestock producers from Utah to extend the results of this and other medusahead control research project occurring in California. We will continue extending project information at future medusahead meetings and through Cooperative Extension publications.
Livestock producers in California frequently inquire to Cooperative Extension about the efficacy of controlling medusahead with the sprayed molasses technique. Now that we have conducted this trial, we are recommending that ranchers and rangeland managers not use this technique, which is valuable information to extend. Information from this project is contributing to a larger body of knowledge on controlling medusahead with intensive grazing that is being developed through research at the University of California and other institutions.
Contributions are explained in the Accomplishments and Outreach sections.
Other research that we have and are still conducting on controlling medusahead shows that properly timed high density grazing is effective. Efforts to achieve the necessary high animal densities will have to rely on fencing, other attractants or other methods of modifying livestock behavior.