Tillage, fertiliser and glyphosate timing effects on foxtail barley (Hordeum jubatum) management in wheat

Abstract

Foxtail barley (Hordeum jubatum L.) is becoming a more severe weed problem as conservation tillage becomes widely adopted on the southern Canadian prairies. A 5-yr field study was conducted to determine the combined effects of tillage, N rate, N placement and application timing of glyphosate to manage foxtail barley in spring wheat. Wide-blade tillage conducted in fall and spring, compared to zero-till, reduced foxtail barley biomass and seed production in all yr and increased wheat yield in 4 of 5 yr. Foxtail barley was highly competitive with wheat for added N. N fertiliser placed mid-row in 10-cm-deep bands reduced foxtail barley growth in 2 of 5 yr and increased wheat yield in 3 of 5 yr compared with soil surface broadcast N. Wheat yield sometimes was similar when N was banded at 60 kg ha−1 or broadcast at 120 kg ha−1, indicating the large advantage of banding N in some situations. Glyphosate at 800 g ha−1 applied preharvest or postharvest gave similar levels of foxtail barley control in 2 of 3 yr. Results indicate that foxtail barley can be adequately managed in wheat production systems utilizing conservation tillage. Key words: Foxtail barley, Hordeum jubatum, glyphosate, integrated weed management, nitrogen placement, zero tillage