Date of Award:

5-2016

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Wildland Resources

Committee Chair(s)

Juan J. Villalba

Committee

Juan J. Villalba

Committee

Karen H. Beard

Committee

Frank E. Busby

Committee

James A. Pfister

Committee

Jong-Su Eun

Abstract

Medusahead is an invasive weed that reduces wildlife habitat and biodiversity as well as commercial and recreational value of land. Grazing represents a sustainable method for its control but stakeholders claim that livestock will not eat medusahead because of its low feed value. This research explored a supplementation program, along with experiences early in life with mother to enhance use of medusahead by sheep. Results showed that an energy supplement did not enhance medusahead use by sheep but that early experience with mother influenced yearlings to use the weed more evenly across days. When availability of the weed was low at pasture sheep did not reject medusahead and consumed the weed in proportion to its abundance. Thus, prudent continuous grazing treatments may be used to reduce the spread of medusahead when the levels of infestation are low (e.g., < 10% abundance). When infestations are high (e.g., > 70% abundance), managers should create grazing cycles where experienced sheep graze medusahead patches for a short time (e.g., 1 day), then a diverse vegetation for 3-7 days, and then medusahead for another short time, mimicking the cyclic pattern of medusahead intake. Finally, ewes that showed a high medusahead use (up to 12%) could be selected to create homogeneous flocks with greater preference for the weed.

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