Weed control in genetically modified sugar beet - two year experiences of a field trial series in Germany

In 1998, a three-year nation-wide series of field trials with the systems R oundup Ready(TM) (RR) and Liberty Link(TM) (LL) in sugar beet was started. The aim of the trial series is to investigate the expected advantages of th ese new weed control systems. A broad range of application timings and rate s of Roundup Ultra(R) (RU, 360 g a.i. L-1 glyphosate) and Liberty(R) (Lib, 200 g a.i. L-1 glufosinate) are tested for efficacy, crop tolerance towards herbicides, yield and quality in comparison to conventional weed control m ethods, which were adjusted according to local weed infestation. The results have shown a good weed control for all herbicide application sy stems under various weed infestation levels all over Germany. Advantages of RU as well as Lib in relation to individual weed species have been observe d. Slight weaknesses of both systems in terms of efficacy were observed in the case of some dicotyledons. White sugar yield results revealed no statis tically significant differences between the various herbicide treatments re viewed.