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Comparison of sugar beet cropping systems with dead and living mulch using a glyphosate resistant hybrid

  • Autor/in: Petersen, J., A.C. Röver
  • Jahr: 2005
  • Zeitschrift: J. Agronomy & Crop Science 191
  • Seite/n: 55-63

Abstract

The aim of this study was to evaluate new options for sugar beet mulch systems, using a glyphosate-resistant hybrid. In four field trials conducted in 2002 and 2003 at two sites in a major sugar beet-growing region in the central Germany three different mulch systems (straw, non-winterhardy and winterhardy cover crop) and an alternative seedbed preparation method (rotary band tillage) have been tested in comparison with a control treatment (plough, no mulch, broadcast seedbed preparation) representing the common German practice. In all systems, a set of eight different weed control programmes, including two reference treatments, one with selective conventional herbicides and five exclusively using glyphosate, has been evaluated for efficacy. It could be shown that the integration of winterhardy cover crops into sugar beet mulch systems reduced the risk of nitrogen loss by leaching. The changes in the nitrogen dynamics neither influence the yield nor the technical quality of the sugar beet. The field emergence of sugar beet decreased while using a winterhardy cover crop, but was not altered by the seedbed preparation method. Compared with the conventional broadcast seedbed preparation, the rotary band tillage did reduce the weed density. The lowest weed density was observed in the straw mulch system. It was not possible to control the remaining plants of the winterhardy cover crops completely with selective herbicides. If glyphosate was used until the four-leaf stage of the sugar beet, a regulation of the winterhardy cover crop was achievable. With glyphosate it was also feasible to control older weeds together with the newly emerging ones with post-emergence applications only. For most of the mulch systems tested, the sugar beet was very sensitive to weed competition between the four- and 10-leaf stage. If the weeds within the sugar beet rows were controlled during this sensitive period with an early glyphosate band application, the remaining weeds between the rows could be left uncontrolled until the 10-leaf stage of the sugar beet without any yield loss. Only in the combination of winterhardy cover crop rotary band seedbed preparation, the weeds and cover crop had to be controlled directly after emergence of the sugar beet.
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