Downy Brome Control in Dryland Winter Wheat with Stubble‐mulch Fallow and Seeding Management1

Abstract

AbstractDifferences in downy brome (Bromus tectorum L.) control had been observed under field conditions of eastern Idaho when dates of stubble‐mulch tillage, final rod weeding, and winter wheat (Triticum aestivum L.) planting were varied. This field‐plot experiment on Tetonia silt loam (Pachic Cryoboroll‐coarse, silty, mixed) tested the degree of downy brome control obtained with three initial stubble‐mulch tillage dates, two final rod weeding dates, and three winter wheat planting dates.Downy brome was best controlled with a combination of initial tilling early in the spring and a final rod weeding just before the late (15 September) wheat planting date. The early tillage killed downy brome before they produced seed. This also resulted in sufficient soil moisture retention in the seed zone for fall germination of other downy brome seeds, which were then killed by the final rod weeding just before the late wheat planting.A reduction in natural downy brome emergence was observed at later fall dates. This was confirmed in a separate field‐plot experiment (Portneuf silt loam, Xerollic Calciorthid, coarse, silty, mixed) where downy brome seed was planted at several dates, and helped explain some of the benefits of the mentioned late rod weeding and planting treatment.These procedures incorporating stubble‐mulch fallow are recommended, as normally practiced moldboard plowing creates an erosion hazard.