ABSTRACT
Genetic engineering has led to the development of crops tolerant of broad-spectrum herbicides. The adoption of these crops has reduced the amount and types of herbicides used for weed management. As with any weed management strategy, shifts in weed densities and species may occur. Field maps depicting changes in weed species or temporal/spatial can be used to assess the effectiveness of the strategy or evolvement of new problems. This case study investigates grass and broadleaf weed densities and species shifts after two rotations (4 years) of glyphosate tolerant corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) in a production Želd. Point data collected from the Želd for 2 years are provided on the accompanying CD in Chapter 16 Žle folder. This case study will show how to summarize the data in MS® Excel and do spatial analyses using geostatistical methods in ArcMap™ (ESRI® Geographic Information System ver. 9.3). Estimates of the spatial extent of grass and broadleaf species in year 1 (Yr1) and year 4 (Yr4) and the shift in species over years are interpolated from point data and extrapolated to unsampled areas.
