Echinochloa crus-galliis a highly competitive annual weed distributed across a wide climatic gradient. Appropriate timing is important for successive control, therefore knowledge about the emergence characteristics can be useful for a decision support system. Emergence of E. crus-galli plants was studied in terms of the common experiment run by the EWRS working group Germination and Early Growth. Seeds from two common populations (Italy and Norway) and 1-3 local populations were sown in 25 cm pots at each of the study sites to monitor emergence. Sowing was done in October- November 2015 and destructive counts were performed every 1-7 days, depending on the site. Soil disturbance with adding fertilizer was performed in March-April 2016. Time after soil disturbance required for the plants of different populations to reach 50% of emergence (T50), the maximum emergence rate (Erate) and the maximum emergence number (Emax) were analysed based on a log-logistic model. For the Italian and Norwegian common populations, interactions between site and population factors were found for Erate and Emax, meaning that these populations behave differently in terms of these two parameters. Norwegian population emerged more and faster in higher latitudes and the Italian one in lower latitudes. For T50, it could be concluded that the Norwegian common population emerged significantly earlier than the Italian one. With respect to the local populations, differences appeared mainly when the habitat of origin varied (crop where the seeds were collected), being those from maize the most similar ones between each other. Usually local populations behaved similar to the nearest, in latitude, common population. These results suggest that a model for the emergence of E. crus-galli could describe properly most populations, but not all, and that populations from different latitudes can have different temperature and humidity thresholds.
