An integrated weed management approach to managing foxtail barley (Hordeumjubatum) in conservation tillage systems

A 4-yr field experiment was conducted to determine the merits of combining cultural and chemical controls to manage foxtail barley in reduced-tillage systems. Factors studied were crop row spacing, seeding rate, and applicati on rate and timing of glyphosate within a spring wheat-flax cropping sequen ce. Glyphosate applied preseeding at 400 or 800 g/ha killed foxtail barley seedlings but only suppressed established perennial plants. Glyphosate appl ied postharvest at 800 g/ha killed 60 to 70% of established plants. Combina tions of preseeding and postharvest glyphosate gave the greatest reductions in foxtail barley biomass and seed production and resulted in the greatest increases in crop yield. Including flax in the rotation allowed use of gra ss herbicides such as quizalofop or sethoxydim that effectively controlled foxtail barley seedlings and provided some suppression of perennial plants. An increase in wheat seeding rate from 75 to 115 kg/ha reduced foxtail bar ley growth and increased wheat yield in 3 of 4 yr. Increasing the flax seed ing rate from 40 to 80 kg/ha or reducing wheat and flax row spacing from 30 to 20 cm provided little benefit in managing foxtail barley or increasing crop yield, A multiyear approach combining agronomic practices and timely u se of herbicides should allow growers to effectively manage foxtail barley in annual cropping systems using conservation tillage.