Agronomic effects from the control of Agropyron repens in barley by pre‐harvest application of glyphosate

Abstract

SummaryPre‐harvest application of glyphosate in barley at 1·44 and 0·72 kg ha−1 was compared with post‐harvest application at 1·44 kg ha−1 at six sites in south‐east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre‐harvest application gave consistent 95–99% control of A. repens compared with 0–76% control from post‐harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre‐harvest treatments and after one post‐harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre‐harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre‐harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre‐harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield losses through tractor wheelings.