Duration of Soil Activity of Foramsulfuron Plus Thiencarbazone-methyl Applied to Weed Species Typical of Sugar Beet Cultivation

Abstract

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.