Between 2004 and 2017, multiple studies on the herbicide resistance of weeds were conducted by the Institute of Plant Protection – National Research Institute in Poland. Weed seeds, collected from fields located in various regions of Poland where herbicide use was ineffective, were used in studies conducted under greenhouse conditions. A total of 261 loose silky bent (Apera spica-venti L.) samples were found to be herbicide resistant, which translates to 52.4% of the fields under study. Nearly 50% of the analyzed samples exhibited resistance to sulfonylurea herbicides. Resistance to acetyl CoA carboxylase (ACCase) inhibitors was found in 18 fields, whereas resistance to photosystem II (PSII) inhibitors (isoproturon) was found in 12 fields. Herbicide resistance of blackgrass (Alopecurus myosuroides Huds.) occurred in 26 of the fields under study. In addition, resistance of wild oat (Avena fatua L.) to acetyl CoA carboxylase inhibitors occurred in 10 spring cereal crops. In the case of winter wheat, resistance of cornflower (Centaurea cyanus L.) to tribenuron-methyl occurred in 23 fields. Scentless chamomile (Matricaria inodora L.) and field poppy (Papaver rhoeas L.) were resistant to tribenuron-methyl in four and three fields, respectively, of winter wheat. In the case of sugar beet, three biotypes of fat hen (Chenopodium album L.) and two biotypes of redroot amaranth (Amaranthus retroflexus L.) were resistant to metamitron. Horseweed (Conyza canadensis L.), which grows on railway tracks, exhibited resistance to glyphosate. This paper reviews all studies conducted in Poland on weed resistance. Based on the results, maps of weed resistance in Poland were created.
The aim of the present work was to evaluate the selectivity of nicosulfuron, alone and in combinations, applied in post-emergence (V4) of glyphosate and sulfonylurea tolerant (RR/STS) soybean. The experiments were conducted in 2015/16 and 2016/17, in Piracicaba – state of São Paulo (SP). In 2016/17, the experiment was also conducted in Palotina – state of Paraná (PR). The experiment was a randomized block design, with four repetitions and 16 treatments, with combinations of nicosulfuron, glyphosate, chlorimuron, sulfometuron and cloransulam, applied alone or in tank mixture. Crop injury and variables related to agronomic performance were evaluated. Data were subjected to analysis of variance and treatment means were compared by the Tukey test. The results obtained are significant in the positioning of herbicides in RR/STS soybean, since in the five experiments, all the treatments were selective, except for glyphosate + sulfometuron which reduced the yield of a cultivar (CD 2630 RR/STS) in the 2015/16 season.