Abstract
Jointed goatgrass (Aegilops cylindrica) is an annual invasive grass weed that infests winter wheat fields in the western United States, resulting in reduced wheat yield and quality. Native to southern Europe and Russia, jointed goatgrass is believed to have been introduced into the United States in contaminated wheat in the late 1800s. Most recent estimates place the number of infested acres in the U.S. at five million, across several western and mid-western states. Research has shown that jointed goatgrass infestations can reduce wheat yields up to 30%. In 2003, yield losses due to jointed goatgrass infestations for the Intermountain region, including Utah, southern Idaho, and parts of Nevada, were approximately 139,000 bushels of winter wheat. Spikelets of jointed goatgrass cannot be completely removed from contaminated wheat grain with conventional sieve-type, or special length-grading seed cleaners. This results in increased dockage and a lower market price when marketing the wheat grain. Jointed goatgrass identification and management are complex issues. Similarity to wheat in appearance and life cycle make jointed goatgrass difficult to accurately identify in the field. Additionally, genetic similarities to wheat make it difficult to selectively control with herbicides. Under conditions of adequate precipitation, wheat is more competitive for resources than jointed goatgrass. However, this relationship reverses once moisture becomes limiting. This is of particular concern in the Intermountain region because of severely limited moisture available for dryland cropping systems. In areas where annual precipitation is less than approximately 15 inches per year, producers generally use a winter wheat-fallow rotation to ensure sufficient moisture for maximum crop yields.