Weed survey 2.0-First results of the recent weed vegetation in maize

The arable land in Germany cultivated with maize increased by about 47% since 2004. The main purpose for maize cultivation is the production of silage maize. High yield losses are caused by competition between maize and weeds. The frequency and occurrence of weeds is determined by environmental, management factors and by the factor growing season (year). To determine current weed assemblage in maize and the farm and field record, a monitoring in maize in Germany was organized by the University of Rostock in cooperation with the Syngenta Agro GmbH. Therefore, in the year 2017, 311 maize fields were assessed nationwide. To determine the current weed assembly, in an unsprayed sampling area of 100 m(2), weed species, number of plants and their ground cover area were identified. When the crop was at its 4- to 8-leaf stage, the assessment was done in 10 time's random sampling squares of 0.1 m(2). Data from all fields were analysed according to their frequency and density per m(2). In comparison to previous monitorings in maize, results of the 15 most frequent weeds show a similar weed assembly, in- and decrease of importance of some weeds, respectively, and some new species in the list. The occurrence and density of Solanum nigrum and Alopecurus myosuroides is mostly limited to the north-western region and the mid and southern regions of Germany, respectively. The results of the weed monitoring 2017 shows first trends of the current weed assembly in maize. To provide more reliable data about weeds in maize, the maize monitoring will be continued in 2018.