The duration of the soil activity of an acetolactate synthase-(ALS) inhibiting herbicide which is currently
under approval for sugar beet cultivation was determined in a field trial series in Germany in 2013
and 2014. The herbicide containing foramsulfuron (FSN; 50 g L−1) and thiencarbazone-methyl (TCM;
30 g L−1) was applied in different dosages (25 + 15, 37.5 + 22.5 and 50 + 30 g FSN+TCM ha−1) to the
bare soil. Five weed species (rapeseed, common lambsquarters, wild chamomile, blackgrass, barnyardgrass)
were sown at 5, 10, 15 and 20 d after application. The duration of the soil activity was assessed by
determining percent weed control in the treated plots. The longest duration was observed after applying
50+30g FSN+TCM ha−1, but the influence of environment was much stronger than the dosage effect.
The mean duration of soil activity was 10 to 15 d in 2013 and longer than 20 d in 2014. Differences
among weed species in their response to the herbicide treatments were small.