Kitchen, B., Agriculture/4-HYouth Agent, Utah State University

ABSTRACT

Foxtail barley is often found in pastures where it displaces desirable grasses. It is undesirable because the awns of mature plants can cause serious injury to grazing animals. In this case study, 16 grass cultivars were evaluated in a pasture renovation situation. The objective of the study was to determine which grasses would be most competitive with foxtail barley. Competitiveness of pasture grasses with foxtail barley was associated with competitiveness with other weeds. Two and three years following establishment, orchardgrass was the most competitive, followed by tall fescue. Competitiveness was not correlated with cattle grazing preference.  The fifth year following establishment, tall fescue cultivars were more persistent with fewer weeds. Orchardgrass cultivars were next in persistence. This study demonstrates that foxtail barley infested pastures can be successfully renovated by using competitive species and careful irrigation and grazing management. 

Introduction

Foxtail barley (Hordeum jubatum) is a short-lived perennial bunch grass that reproduces by seed. It is adapted to a variety of soil conditions including saline and poorly drained soils. Yet, it is able to survive periods of drought. It grows one to two feet tall and has a spike with long awns. Foxtail barley is often found in pastures where the awns of mature plants can cause serious injury to a grazing animal’s eyes, nose, throat and ears (9,12).  Chemical control of foxtail barley in established cool-season grass pastures is limited. Although pronamide (Kerb) provides adequate control and safety to desirable grasses, it is not labeled for pastures in the U.S. (10). Therefore, control of foxtail barley in pastures involves efficient irrigation management and careful grazing management to maintain desirable species. It is generally recommended that seriously infested pastures be renovated (9,11). Attempts to renovate pastures can be unsuccessful, even though foxtail barley can be killed with tillage or herbicides, because seeds remaining near the soil surface often germinate with the seeds of desirable grasses. Foxtail barley seed viability declines rapidly after three years (4). Therefore, the probability of successful pasture renovation should be increased by selecting improved grass species that establish quickly. Prevention of viable seed production in the first few years after renovation should effectively deplete the foxtail barley seed bank. 

Whitson and Langbehn (13) reported differential competitive effects with five cool-season grasses. In their research they found that ‘Jose’ tall wheatgrass and the experimental line, RS1 hybrid wheatgrass, were competitive with foxtail barley. This study was conducted to further identify grass cultivars which can compete with foxtail barley in a pasture renovation situation.

Materials and Methods

An irrigated pasture infested with foxtail barley was chosen as the site for the study. The site is located near Vernal, Utah (40°29’N, 109°31’W, elevation 5271ft). The soil at the site is a Crib loam (coarse-loamy, mixed, superactive, mesic Aquic Haplocalcid), is somewhat poorly drained, has moderate water holding capacity and an extremely cobbly subsoil. The top 2 feet of soil holds about 3 inches of available water, only half of which is readily available. In mid summer, cool season grasses use about 1.5 inches of water per week in Vernal (3). Therefore, irrigation intervals longer than once per week can result in drought stress.

Seedbed preparation included spraying existing vegetation with 2.25 lb/acre of glyphosate, disking six days later and firming the seedbed with a culti-packer. Seed was drilled in rows spaced six inches apart on May 22, 2002. Plots were 8 ft wide and 20 ft long. Four replications of 16 cultivars were planted in a randomized complete block design. Cultivars included ‘Johnstone’, ‘Fawn’, ‘Select’, ‘Tuscany II’, ‘AU Triump’, ‘Martin 2’, ‘Houndog’, and ‘EA30’ tall fescue; ‘Manchar’ and ‘AZ11’ smooth bromegrass; ‘Potomac’ and ‘Crown Royale’ orchardgrass; ‘Regar’ meadow bromegrass;‘Garrison’ creeping foxtail;‘MP211 4N’ perennial ryegrass;and ‘Newhy’ hybrid wheatgrass.  Seeding rate was determined by species and is reported in Table 1. The border area of this experiment was broadcast seeded with ‘Fawn’ tall fescue at the rate of 30 lbs/acre.

The plot was irrigated with sprinklers. Growing season precipitation plus irrigation totals for 2002, 2003 and 2004 were 26, 24 and 23 inches, respectively. Frequency of irrigation varied according to water availability.

No grazing was permitted in the establishment year but the plots were clipped in the fall to a height of 2 inches to control weeds. In June of 2003, the plots were sprayed with a mixture of 0.5 lb of 2,4-D and 0.19 lb of clopyralid per acre to control broadleaf weeds.

No fertilizer was applied during the establishment year. In 2003 and 2004, split applications of nitrogen were applied as ammonium nitrate. The first application was made in the spring and the second in mid summer. In 2003, 90 and 60 lb of nitrogen were broadcast per acre. Because the plots showed signs of nitrogen deficiency the amount of fertilizer was increased in 2004 to 100 lb of nitrogen per acre in each of two applications.

Competitiveness of seeded grasses with foxtail barley and with  other weeds was determined in May, July and August in 2003 and in May and August in 2004.  Competitiveness with foxtail barley and other weeds was rated on a scale of 1 to 9 (1 = heavily infested, 9 = no weeds). Figure 1 shows two adjacent plots which were rated at the extreme ends of the scale. Ratings were averaged across five dates for foxtail barley competitivenss and across 4 dates for other weeds.

Figure 1. Example of visual ratings for foxtail barley infestation. The plot on the left was rated 1, highly infested; the plot on the right was rated 9, not infested.

Grazing preference was rated on a scale of 1 to 9 (1 = not grazed, 9 = all grass was grazed to a stubble height of less than 2 inches). The rating was made following a 30 day rest period, followed by 4 days of grazing by 16 yearling steers in the plot area of approximately one acre. The rating may have been influenced by the weediness of the plot and therefore may not have been reflective of the grazing preference of a pure stand of the seeded cultivar. Following the grazing period, the plots were clipped to a 2 inch stubble height to eliminate foxtail barley seed production.

After gathering data in 2004, management of the pasture was returned to the landowner. Irrigation according to water availability, occasional fertilization, and grazing management which varied from continuous grazing to periodic grazing with rest periods characterized the management in 2005 and 2006. In the spring of 2007, persistence was determined as the percent cover of seeded grasses by counting the frequency of seeded grasses at 1 ft intervals on line transects made by stretching a measuring tape between opposite corners of the plots. 

Analysis of variance and mean separation (Least Significant Difference for alpha=0.05 and 0.2) were accomplished using Statistix (Analytical Software, Tallahassee, FL). Analysis was done on the average of five and four observations for foxtail barley rating and other weeds rating, respectively. Observations were averaged before analyzing because the primary interest was in the effect of cultivars.

Relationship between infestation by foxtail barley and infestation by other weeds was tested to see if cultivar differences in infestation were general in nature or specific to foxtail barley. Relationship between infestation by foxtail barley and cattle preference was also tested. Relationships were tested using the Pearson correlation procedure.

Results and Discussion

Orchardgrass was the most competitive with weeds including foxtail barley. The tall fescue varieties were next (Table 2). Foxtail barley ratings and other weeds ratings were correlated to each other (r = 0.796, P<0.01) indicating that pasture grasses that competed well with foxtail barley also competed well with other weeds.

There was little difference between cultivars of the same species for foxtail barley or other weed ratings. There were some differences among tall fescue varieties. ‘Select’ and ‘Tuscany II’ were among the most competitive while ‘EA30’ and ‘Houndog’, both turf-type cultivars, were less competitive.

During the summer of 2003, irrigation was reduced to one irrigation every two weeks due to a limited water supply. Drought stress was observed in portions of some plots. Investigation of the soil profile indicated a gravel lens at approximately two feet deep in the affected plots. Orchardgrass and perennial ryegrass plots were most affected. Tall fescue showed more drought tolerance. Foxtail barley was one of the more drought tolerant species and dominated in the drought affected plots. This observation suggested the importance of careful irrigation management in controlling foxtail barley.

Cattle preference seemed to have little impact on the ability to compete with foxtail barley (r = 0.172, P=0.17) or with other weeds (r = 0.054, P=0.674), orchardgrass being the most preferred of the pasture grasses and tall fescue being the least preferred. ‘Johnstone’ was an exception to the low grazing preference for a tall fescue with the third highest grazing preference rating.  Several authors have reported that foxtail barley is relatively palatable and nutritious at young stages (10,11). In this study, all of the pasture grasses were preferentially grazed compared to foxtail barley. This was observed before foxtail barley headed. Cattle began to graze foxtail barley at about the same time they began to graze the least preferred tall fescue cultivar.  This suggests that renovated pastures previously infested with foxtail barley will need careful grazing management to keep foxtail barley from returning to dominance.

Foxtail barley was essentially eliminated from all treatments by the spring of 2007.  Apparently, management was sufficient to preclude the re-establishment of foxtail barley. Factors which contributed to the success were frequent mowing to prevent viable seed formation, controlled irrigation and competition from desirable species.

Tall fescue persisted better than the other grasses five years after seeding (Table 2). Orchardgrass was next in persistence. The persistence of tall fescue may be the result of several factors including deeper rooting depth and lower palatability when compared with other pasture grasses (6). In addition, tall fescue has been reported to exhibit allelopathic effects on some species in mixed swards (2,7,8). It may be interesting to note that the most persistent tall fescue cultivar was ‘Houndog’ a turf type cultivar infected with a fungal endophyte. Endophyte infection is reported in the literature to increase persistence of tall fescue pastures (1,5).

During the study it was noted that the border of the study area which had been broadcast seeded with tall fescue at double the normal seeding rate had a very low level of infestation of foxtail barley.

Conclusions and Recommendations

Orchardgrass and tall fescue are two species to be considered when renovating pastures infested with foxtail barley. In the Intermountain West, many pastures will have areas with droughty or saline soils. In these areas, tall fescue may be more persistent and competitive with foxtail barley than orchardgrass. Cultivars which establish quickly and have the best vigor will likely be best. Increasing seeding rate may add to the competitiveness of desirable grasses with foxtail barley.

Literature Cited

1. Bates, G. Tall fescue, orchardgrass and timothy: cool-season perennial grasses. Online. Agricultural Extension Service, University of Tennessee.  Bulletin SP434-E. https://utextension.tennessee.edu/publications/Documents/SP434-E.pdf .

2. Butal, J. G. and Spaulding, D. W. 1989. Allelochemicals in tall fescue-abscisic and phenolic acids. J. of Chem. Ecol. 15 (5): 1629-1636.

3. Consumptive Use of Irrigated Crops in Utah. 1994. Research Report 145. Utah Agricultural Experiment Station, Utah State University. Logan, Utah.

4. Dunn, R. and Blackshaw, R. 2007. Foxtail barley control in direct seeding. Online. Alberta Agriculture and Food. http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex856 .

5. Hoveland, C. S., Bouton, J. H. and Durham, R. G. 1999. Fungal endophyte effects on production of legumes in association with tall fescue. Agron. J. 91(6): 897-902.

6. Jensen, K., Horton, H., Reed, R., and Whitesides, R. 2001. Intermountain Planting Guide. Page 53. USDA-ARS-Forage and Range Research Lab. Logan, Utah

7. Luu, K. T., Matches, A. G. and Peters, E. J. 1982. Allelopathic effects of tall fescue on birdsfoot trefoil as influenced by N fertilization and seasonal changes. Agron J. 74:805-808.

8. Peters, E. J., and Zam,  A. H. B. M. 1981. Allelopathic effects of tall fescue genotypes. Agron J. 73:56-58.

9. Pratt, M., Bowns, J., Banner, R. and Rasmussen, A. 2002. Range plants of Utah: Foxtail barley. Online. Utah State University Extension. http://extension.usu.edu/range/Grasses/foxtailbarley.htm .

10. Reid, C. R., Winward, D. L., and McDonough, R. M. 2011. Evaluating control of foxtail barley (Hordium Jubatum) and desirable grass compatibility in irrigated pasture using Kerb herbicide.  Online. National Association of County Agricultural Agents. http://www.nacaa.com/ampic/2011/Western%20Region%20Meeting%20Proceedings%202011.pdf

11. Tremblay, M. 2004. Foxtail barley in forage and pasture. Online. Government of Saskatchewan. http://www.agriculture.gov.sk.ca/Default.aspx?DN=d759f6e8-b1e7-4f75-9632-8aa14e1059e3 .

12. Whitson, T. D., Burrill, L. C., Dewey, S. A., Cudney, D. W., Nelson, B. E., Lee, R. D., and Parker, R. 2000. Foxtail barley and squirreltail. Pages 454-455 in: Weeds of the West, 9th Ed. The Westerrn Society of Weed Science, Newark, CA.

13. Whitson, T. D., and Langbehn, J. M. 2001. The competitive effects of five cool-season perennial grasses on foxtail barley. In College of Agriculture – Agricultural Experiment Station Progress Report. Pages 231-232. University of Wyoming.

 

 

         

 

 

 

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