Integrated Weed Management Systems Identified for Jointed Goatgrass (Aegilops cylindrica) in the Pacific Northwest

Abstract

Jointed goatgrass is an invasive winter annual grass weed that is a particular problem in the low to intermediate rainfall zones of the Pacific Northwest (PNW). For the most part, single-component research has been the focus of previous jointed goatgrass studies. In 1996, an integrated cropping systems study for the management of jointed goatgrass was initiated in Washington, Idaho, and Oregon in the traditional winter wheat (WW)–fallow (F) region of the PNW. The study evaluated eight integrated weed management (IWM) systems that included combinations of either a one-time stubble burn (B) or a no-burn (NB) treatment, a rotation of either WW–F–WW or spring wheat (SW)–F–WW, and either a standard (S) or an integrated (I) practice of planting winter wheat. This study is the first, to our knowledge, to evaluate and identify complete IWM systems for jointed goatgrass control in winter wheat. At the Idaho location, in a very low weed density, no IWM system was identified that consistently had the highest yield, reduced grain dockage, and reduced weed densities. However, successful IWM systems for jointed goatgrass management were identified as weed populations increased. At the Washington location, in a moderate population of jointed goatgrass, the best IWM system based on the above responses was the B:SW–F–WW:S system. At the Washington site, this system was better than the integrated planting system because the competitive winter wheat variety did not perform well in drought conditions during the second year of winter wheat. At the Oregon site, a location with a high weed density, the system B:SW–F–WW:I produced consistently higher grain yields, reduced grain dockage, and reduced jointed goatgrass densities. These integrated systems, if adopted by PNW growers in the wheat–fallow area, would increase farm profits by decreasing dockage, decreasing farm inputs, and reducing herbicide resistance in jointed goatgrass.

Development of Dryland Oilseed Production Systems in Northwestern Region of the USA

“…In the CP, the integration of fertilizing near or at time of planting, planting a competitive variety, increasing seeding rate, and growing winter wheat every 3 years both decreased jointed goatgrass density and increased grain quality and yield [158]. These benefits were realized without any in-crop grass herbicide.…”

Economics of Alternative Management Practices for Jointed Goatgrass in Winter Wheat in the Pacific Northwest

“…For data presentation, means were back‐transformed. The SAS Proc Mixed procedure was used to analyze the data and Hsu' multiple comparison with the best procedure (3,18) selected the treatment combinations into a subset such that the best treatment combination is included in the subset with a 95% level of confidence.…”

“…Average baseline jointed goatgrass spikelet density was 66 (0.25 yd 2 soil surface plus soil cores to 8 inches) for the west experiment and 24 for the east experiment. Burning wheat stubble reduced spikelet density in the west experiment 60% and seed viability 90% (18). Spikelet density and seed viability was reduced 15% and 95% respectively in the east experiment ( data not shown ).…”

“…Agronomic data will be analyzed separately for each experiment and the four barley systems will be analyzed separately from the eight wheat systems. Jointed goatgrass populations and crop yield and quality from the west experiment's eight wheat production systems have been discussed previously (18). The overall best production system for reduced weed densities and highest grain yield and quality was the B:SW‐F‐WW‐F:S system.…”

“…Past JGG control research has focused on single‐component studies such as the effects of crop rotation on wheat yield and jointed goatgrass populations (2); competitive wheat cultivars (11), and increased seeding rate and increased seed size (5); fertilization (7), and stubble burning (19). Recently a study was conducted in the winter wheat‐fallow (WW‐F) region of the Pacific Northwest (PNW) that identified complete Integrated Weed Management (IWM) systems for jointed goatgrass control in winter wheat (18). However, after decades of research, there has been no empirical economic evaluation of jointed goatgrass in wheat production regions in the United States.…”