Violett Randall D., Ecology and Control of Foxtail Barley (Hordeum jubatum L.) on Irrigated Pastures in the Big Horn Basin, Wyoming. Ph.D., Department of Plant Sciences, December, 2012. Foxtail barley is invasive to irrigated pasture and wet meadow habitats in the Western United States. In pasture settings, foxtail barley rapidly forms monoculture stands that displace favorable vegetation. On much of this land, it is not feasible to apply tillage practices because of poor drainage conditions or shallow soils. Therefore, landowners are seeking an integrated management program to control foxtail barley in their pastures. A four year field experiment was conducted at two locations in Northwest Wyoming to evaluate management strategies that control foxtail barley and re-establish desirable vegetation. Locations were selected based on foxtail barley infestation level, soil conditions, and the common management of livestock grazing. Soil edaphic conditions including pH, electrical conductivity (EC), and texture were used as indicators of the presence of foxtail barley infestations. The management strategies include imazapic application on pastures with and without nitrogen fertilizer application to selectively control foxtail barley without affecting the desirable pasture grasses present. A split application of imazapic at 70 g ai ha-1 in May and then again in June was very effective in reducing foxtail barley biomass by 56 to 73% and suppressing seed head production by 95 to 98%. Seed head suppression was a desirable response to herbicide application because it reduces seeds in the soil seed bank. The use of imazapic also provides the landowner with the opportunity to continue to utilize the pasture because of no grazing restrictions for imazapic. Fertilization of pastures with 67 kg ha-1 nitrogen increased the effectiveness of imazapic by 14%. Foxtail barley was found to be associated with soil pH of 8.0 to 8.1, EC of 4.9 to 6.8 ds m-1 and silty clay loam texture (32 and 43 to 47% clay and sand content, respectively). Based on these results, landowners interested in raising livestock on their land parcels should conduct soil tests before making decisions on pasture renovation. Fertilization and imazapic application will assist the landowner in restoring an irrigated pasture without the need of total renovation or tillage to control foxtail barley.
|Advisor:||Miller, Stephen D., Mesbah, Abdelouhab|
|Commitee:||Delaney, Ronald H., Jacobs, James, Kniss, Andrew|
|School:||University of Wyoming|
|School Location:||United States -- Wyoming|
|Source:||DAI-B 74/05(E), Dissertation Abstracts International|
|Subjects:||Agronomy, Plant sciences|
|Keywords:||Big horn basin, Foxtail barley, Hordeum jubatum, Imazapic, Seed head suppression, Wyoming|
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