Weed mapping methodologies are being tested in agricultural fields to generate maps of spotted application of herbicides by using precision farming tools. Weed mapping may generate herbicide treatment maps, allowing herbicide spray only where needed. However, few experiments have reported the efficiency of these methods. This research aimed to compare Panicum maximum mapping methodologies based on visual assessment during and after corn harvesting. Monitoring combined with visual assessment was performed during harvesting by a duly trained worker and a previously oriented operator. Visual assessment was done by samplings after harvesting in a regular 20 x 20 m grid. An underestimation of 6% of the infested area was observed, with infestation over 80%, by the mapping method during harvesting. The two methods were coincident in 45% of the area studied.
precision farming; weed mapping; site specific management
