Adverse effects of weeds in coverless lucerne crops.
The most widespread weeds in 1st-year lucerne in the central forest steppe zone of Ukraine are barnyard millet [Echinochloa crus-galli] and yellow foxtail [Setaria pumila]. Investigations over 3 years in which these weeds were allowed to grow at different densities in lucerne produced for green fodder showed clear correlations between yield and both the number and weight of the weeds. Even 5 weeds per m2 resulted in a yield reduction of 16.4%. Post-em. application of Bazagran [bentazone] (2 litres/ha) and Nabu [sethoxydim] (3 litres/ha) killed 88% of the weeds, and weediness in the following year was minimal. Economic thresholds were calculated for the application of these chemicals.