To provide quantitative support for the decision on whether or not a c
rop of sugar beet (Beta vulgaris L.) has to be resown after poor estab
lishment, the effect of plant density (2 to 9 plants per m2) on sugar
yield was investigated in six experiments in two consecutive years on
three sites in the north, south-west and central regions of the Nether
lands. Sowing dates, seedbed preparation and sowing were varied to pro
duce a situation in which the effect of resowing could be analysed. Pl
ant density influenced sugar yield more in the trials in the north and
south of the country than in the central region on reclaimed marine s
oil. The effect of sowing date on sugar yield was analysed with a simu
lation model based on temperature and intercepted radiation. Yield los
s caused by a later sowing date can be estimated by multiplying the th
ermal time between two sowing dates by a constant (1.31) that is the y
ield loss in g sugar per m2 per degrees-C day. As plant stage of the f
irst-sown crop is also strongly related to thermal time, the yield los
s due to a later resow date may be estimated using the plant stage of
the crop to be resown.