Danish winter wheat demonstration trial 2018/19, WP3

In season 2018-2019, the demonstration trial is located in fields belonging to VKST (local advisory service), where an area with a range of winter wheat trials is assigned to demonstration and will have a large number of visitors during the growing season. The IWMPRAISE demonstration trial was established in September 2018 and includes strategies with different sowing dates, variable sowing density, direct sowing, mechanical and chemical weed control.

The direct sowing (strategy 4) did not establish well and it was decided to cancel this strategy in early spring. In some areas of the strategy no plants emerged at all. Therefore, there are no direct sowing in the final results from 2018. Only 93 pl/m² was counted in Nov. 2018, where emergence was fair, compared to 163 pl/m² in the standard strategy. The strategy with no herbicides and weed hoeing (strategy 5) was not successful this season. Wet conditions in spring made weed hoeing impossible in March and by the time the soil was dried (mid April) it was too late to have satisfactory control of the weeds (picture 1). A strategy with wider rows and weed hoeing has previously proved successful in several trials, but it requires good timing. Furthermore, a row distance lower than 20 cm is to prefer. This year the row distance was 25 cm due to available sowing machines and weed hoeing tools. The sowing density was increased to promote the crop competition in the row, which is evident from the plant density observed in autumn (243 pl/m²). The biomass of crop and weed, respectively, is presented in figure 1. All the strategies with herbicides showed good weed control, however, some weeds in the early sown strategy was not sufficiently controlled in spring. The reason was later emerging weed species or weed species not targeted with the herbicide choice in spring. In the standard strategy and the high-density strategy (strategies 1 and 2), no herbicides were applied in spring.

Picture 1: Strategy with weed hoeing (strategy 5) in late May.

A national cluster meeting among the project partners was held in June and the outcome of the season so far was discussed. Potential adjustments was discussed for the next season. There was a general interest in continuing the work with weed hoeing, possibly in combination with band spraying. Next year’s strategies will be presented later in 2019.

Figure 1: Crop (green) and weed biomass (red) in late June 2019. Numbers in the boxes indicate plant density in November 2018. The strategies from left to right is: standard winter wheat sowed in mid Sep. with autumn + spring herbicide application, standard strategy with increase sowing density (+50%), standard strategy with early sowing (start Sep.) and finally a strategy with weed hoeing on wider row distance. It is a demonstration trial, and the replications are only pseudo replicates as the data is collected four places in the same stripe through the field. This layout was chosen to get a good visual impression in the demonstration trial.

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