In a summary of 15 years of field data in Eastern Washington, Nevin Lawrence, former Ph.D. weed science student studying under Dr. Ian Burke, found that Outrider, Olympus, and PowerFlex all provided superior downy brome control when applied in the fall rather than the spring (see figure). Downy brome control did not differ for Beyond applied fall or spring. Beyond may only be applied to Clearfield wheat varieties.
What has been reported for downy brome (see figure 1) is likely also true for the other winter annual grass weeds. So whether your problem is with downy brome, jointed goatgrass, or feral rye, the fall is almost always the best time to implement control measures, especially when early fall rains bring these weeds up in September or October.
For more information on controlling downy brome in winter wheat, including herbicide recommendations, see Integrated Management of Downy Brome in Winter Wheat, a Pacific Northwest Extension Publication – PNW668. Similar information is available for jointed goatgrass and feral rye.