Soil activity of post-emergent herbicides recommended for black-grass and loose silky-bent grass control in winter wheat
2012
Meiners, Ingo | Krähmer, Hansjörg | Honermeier, Bernd
The natural emergence of black-grass (Alopecurus myosuroides) was observed on a wheat field over two growing seasons in 2009 and 2010. Under shallow tillage conditions, A. myosuroides emerged steadily between the months September and May. Peak emergence occurred after sowing until the middle of October followed by continuous emergence until winter. Another peak of emergence took place in spring through the beginning of May. Under conventional tillage conditions (ploughing) in 2010, almost no germination of A. myosuroides could be observed after the first herbicide treatment in autumn. In order to evaluate the soil activity of recommended post-emergence herbicides, two pot experiments with sterilized soil were carried out outdoors and under greenhouse conditions. The results show that all tested grass herbicides, ACCase-inhibitors and ALSinhibitors, demonstrated strong soil efficacy against A. myosuroides and Apera spica-venti in most cases. Especially the herbicides propoxycarbazone, pyroxsulam and mesosulfuron-methyl showed a high soil activity even at low doses. While the soil activity was consistent for clodinafop-progagyl, variable results were observed for fenoxaprop-P-ethyl and pinoxaden in the two experiments. We conclude that the soil activity of the tested herbicides is very variable and dependent on many factors which make it difficult to predict their activity especially under field conditions.
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