Changes in Weed Communities, Herbicides, Yield Levels and Effect of Weeds on Yield in Winter Cereals Based on Three Decades of Field Experiments in South-Western Germany

Publication Type

Working paper

Authors

M. Keller, N. Böhringer, J. Möhring, V. Rueda-Ayala, C. Gutjahr and R. Gerhards

Year of publication

2015

Published in

Gesunde Pflanzen

Band/Volume

67/1

ISBN / ISSN / eISSN

0367-4223

DOI

10.1007/s10343-014-0335-8

Page (from - to)

11-20

Arable cropping practices including chemical weed control changed considerably over the last decades in south-western Germany affecting weed communities and weed-crop interference.

Data of weed control experiments in winter cereals were analysed to determine changes in weed frequencies, applied herbicides and yield over the last three decades. The effect of weeds on yield and economic thresholds (ETs) were determined based on 122 trials for wheat and barley.

In the 1980s, herbicides belonging to the HRAC-groups C, K, M and O; in the 1990s and 2000s to the HRAC-groups A, B and F were dominant. Nevertheless, weed communities were rather stable in winter cereals. Galium aparine and Stellaria media decreased in frequency. Alopecurus myosuroides frequency increased but densities remained stable. ETs ranged from 9.2 to 9.8 % and 4.5 to 8.9 % absolute weed coverage for wheat and barley correspondingly. Without weed interference yield increased by 0.16 t ha⁻¹ a⁻¹ for wheat and 0.08 t ha⁻¹ a⁻¹ for barley. In the control plots, where weeds competed with the crop, yields did not increase. Yields in the “best” herbicide treatment were 1.5–2.3 t ha⁻¹ higher than in the control plots. This emphasizes the importance of effective weed control in winter cereals.