The Sugar beet recommended list provide some guidance as to the numbers of bolters to be expected from each variety. Fodder beet growers don’t always have that amount of detail available to them. However good management can reduce the occurrence of bolters, recover lost production and hence profitability.
Trials using different varieties show that early-bolting plants which form true seed stalks produced only about half the yield of roots when compared to a normal plant.
Using British Sugar bolting tables and then “averages values” we have the following figures to consider:-
Beet plant population = 100,000 / ha
Fresh wt crop of 75 t/ha from 100,000 plants.
That means one plant weighs 0.75 kg
Bolters represent 0.1 to 20% of the plants
(100 to 20,000 / ha)
50% of average wt = 0.375 * 100
= 37.5 kg/ha yield penalty
50% of average wt = 0.375 * 20,000
= 7.5 t/ha yield penalty
A few key points to consider are:-
Drill early for 5-10% extra yield, but expect more bolters
With 1% of your crop as bolters expect 1t/ha loss in field yield as part of the weed beet legacy
Bolting is severe two years out of last 10.
Bolter numbers depends on temperature.
The cumulative amount of cold between drilling and the end of May determines risk.