The post-emergence herbicide treatments were carried out on 1 July in 2014 and on 4 July in 2015 using a herbicide rate of 2 l ha-1 with active ingredient (a.i.) mesotrione (150 g a.i. ha-1) and nicosulfuron (60 g a.i. ha-1), in the areas to be treated for both growing seasons. The delay between UAV acquisition and herbicide treatment was due to technical problems concerning the availability of the herbicide to the farmer. However, based on field observations carried out during this lapse of time, the spatial distribution of weeds did not vary much during this period. Maize was about at V6 phenological stage at herbicide treatment time, while C. rotundus was at the beginning of the flowering stage (BBHC 5).