Jointed goatgrass (Aegilops cylindrica) is an annual invasive grass weed that is particularly troublesome in winter wheat fields in the western United States. The severity of the infestation has increased over the past 50 years in many areas to levels that reduce yield and quality significantly. Native to southeast Europe, jointed goatgrass is believed to have been introduced into the United States in contaminated wheat in the late 1800s. Spikelets of jointed goatgrass cannot be completely removed from contaminated wheat grain with conventional sieves or with special length-grading seed cleaners. This has prompted the grain industry to increase the penalty when goatgrass spikelets are part of the dockage, which further lowers the market price of contaminated wheat.
Although jointed goatgrass is a major problem in most winter wheat growing areas west of the Mississippi River, the climate and cropping patterns of the Pacific Northwest (PNW) are unique and may influence the choice of options available for effective management of this pest. In particular, producers have noted that by adopting direct seed/reduced tillage management systems, both the number of jointed goatgrass infestations and the densities of these infestations tend to increase.
Jointed Goatgrass Biology
Jointed goatgrass is a winter annual grass weed that closely mimics the life cycle of winter wheat, and has a similar life cycle to other grass weeds of importance such as downy brome
Seed can remain viable in the soil for up to five years (Figure 3), especially in drier regions and when deeply buried. Seed will typically decay faster in a region with higher precipitation. A study in the PNW showed that seed remained viable for more than five years in a 10-inch rainfall area, compared to less than three years in a 22-inch rainfall area. In addition, most jointed goatgrass seed will germinate and emerge from soil depths as great as two inches. Approximately 80% of the seed placed between the surface and a depth of two inches will germinate within three years. Some seed will emerge from depths of two to three inches, but very few will emerge from soil depths greater than four inches. The optimum temperature