EFFECT OF TIME OF WEED EMERGENCE ON COMPE TITION BETWEEN SUGAR-BEET AND FAT HEN (CHENOPODIUM-ALBUM L) - FIRST RESULTS

In a field trial near Gottingen different densities of Chenopodium alb um emerged at different development stages of sugar beet were establis hed. When the period between emergence of crop and weed increased, gro wth of Chenopodium album was reduced. Chenopodium album emerged at the 2-4 leaf stage of sugar beet reached an average height of 139 cm, a m aximum shoot diameter of average 41 cm and a biomass of 68 g dry matte r per plant. Emerged at the 6-8 leaf stage and the 10-12 leaf stage th e average height of Chenopodium album was only 97 and 48 cm, the maxim um shoot diameter 15 and 10 cm and the biomass 12 and 1 g dry matter p er plant. A significant loss in white sugar yield caused by these diff erences in growth pattern occurred at a density of 0.6 Chenopodium alb um per m(2) emerged at the 2-4 leaf stage. However, emerged at the 6-8 leaf stage no yield loss appeared even at the highest density of 2.2 plants per m(2). By taking into account the period of weed emergence y ield loss could be described suitably by weed density. The quality of sugar beet was not affected by the weed densities tested.