SITE-SPECIFIC WEED-CONTROL IN WINTER-WHEAT

Field experiments were conducted in two winter wheat fields to assess weed control and quantify the amount of herbicide applied with a GIS m ap-based patch sprayer. Site specific weed management decisions were b ased on previously acquired weed distribution maps and an economic wee d threshold model. A weed treatment map (on-off) was generated and geo referenced to control the sprayer. A global positioning system was use d to locate the sprayer in the field. In both fields, Alopecurus myosu roides was observed at low infestation levels, Galium aparine at mediu m infestation levels and the mean density for other broadleaf species exceeded 40 weed seedlings m(-2) in both fields. Herbicide application was recommended for 58.3% of the first held and 54.6% of the second f ield. With the patch sprayer used for this study, 21% less herbicides were sprayed compared to an uniform broadcast application. Additional assessments of weed density in the first field 3 and 6 weeks after sit e specific weed control showed that almost the entire field was weed f ree. The results of this study demonstrated that site specific weed co ntrol was technically feasible but further investigations are needed t o verify and evaluate site specific weed control methods.