WERA_OLD077: Managing Invasive Weeds in Wheat
Statement of Issues and Justification
Invasive weeds currently infest more than 20 million acres of winter wheat in the Western United States, costing producers over $500 million in yield losses annually (T. White, 2003. Unpublished survey data). Heavy infestations of weeds may result in complete crop failure while lighter populations decrease yield, increase dockage, and decrease harvesting efficiency. Downy brome (Bromus tectorum) and jointed goatgrass (Aegilops cylindrica) remain troublesome weeds in winter wheat production regions. However, feral rye (Secale cereale), ryegrass species (Lolium spp.), cheat (Bromus secalinus), and rip gut brome (Bromus diandrus) also threaten the economic viability of winter wheat production.Turf and forage ryegrass varieties are very competitive for resources and can quickly invade desirable vegetation and crops, like wheat, if not properly managed (Anonymous 2002). Various selective herbicides are available to control ryegrass in conventional wheat, but few are registered in dual-purpose wheat. In the Southern Great Plains, as much as 80% of wheat is grazed during the growing season (Pinchak et al. 1996). Grazing restrictions severely limit or prohibit the use of most effective herbicides in dual-purpose wheat.
In 1987, ALS-inhibitor herbicide resistant ryegrass was documented in Oregon and since then has been confirmed in eight additional states (Heap 2004). Subsequently, resistance to other herbicide classes has been documented in the United States (Tucker 2002; DePrado et al. 2000; Moss et al. 1993; Stanger and Appleby 1989). In other countries glyphosate resistant ryegrass as well as multiple herbicide resistance has been discovered (Kuk et al. 2000; Roman et al. 2003). Current economic losses from ryegrass infestations exceed $30 million in the Western United States due to reduced yield, increased grain dockage, and lower land values (T. White, 2003. Unpublished survey data).
Rye is grown as a crop in many regions of North America. However, it can become a troublesome weed for wheat producers. Feral rye, commonly referred to as cereal, winter, common, or volunteer rye, is found in various wheat production areas throughout the Western United States (Lyon et al. 2002). Currently, there is no commercially acceptable way to selectively control feral rye in conventional (non-herbicide tolerant) wheat. Reduced profits often exceed $26 million in the Western United States due to lower yields, dockage, and reduced land value (T. White, 2003. Unpublished survey data).
In order to develop best management practices for the control of feral rye, ryegrass, and other invasive weeds in wheat, a thorough understanding of weed biology, ecology, and genetics is required. Sharing research information and coordinating research and extension efforts among weed scientists in the western United States will accelerate understanding of invasive weeds and their control and facilitate the rapid transmission of new knowledge to growers. Currently, management information regarding ryegrass and feral rye is limited. The overall goal of this coordinating committee is to ensure that producers have the most accurate, non-biased information possible for economical and sustainable management of feral rye, ryegrass, and other invasive weeds in wheat.
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