II.3. BRASSICA CROPS (BRASSICA SPP.) – 179
Figure 3.27. Percentage of the total Canadian B. napus production area sown to
herbicide resistant varieties, 1995-2008Note: HR = herbicide resistant.
Source: Adapted from Beckie (2011).
The double disc grain drill has now been largely replaced by large air seeders that
place the seed and fertilizer some 2-3 cm below the soil surface, at a seeding rate of
5-8 kg per hectare. Seed is treated with an insecticide-fungicide coating. The herbicide
glyphosate is usually spring applied prior to seeding to control early germinated or
biennial weeds. In North America, seeding generally occurs in early May. The herbicide
of choice is applied at the recommended rate when the weeds are small and the leaves of
the B. napus plants have not fully covered the ground. B. rapa fields begin flowering in
mid-June while B. napus fields begin to flower about two weeks later in late June or early
July. Recommended fungicides and/or insecticides may be applied as a spray if the pest
incidence warrants. At harvest, in late August through September, the crop is normally
swathed into windrows to allow more uniform ripening and to protect against seed losses
due to pod shatter. Combining the swaths is done when the seed is mature and dry.
However, some straight combining of the standing crop is also practiced. Usually the seed
is farm stored at less than 9% moisture until marketed.
Chile is the only country in South America that produces a significant quantity of
oilseed rape with planting of winter and spring B. napus on some 17 000 hectares in the
southern provinces of the central part of the country. The crop is predominantly winter
B. napus. The winter crop is sown in March and April, flowers in October and November
and is harvested by straight combining in January. Winter kill may occur in May or June
due to the wet soil freezing and heaving, causing broken roots. The spring crop is sown in
August-September, flowers in October and is harvested in late December or early
January. The crop is normally sown on land broken out of grass pasture using a disk or
mould board plough, disked twice with a double disk cultivator and packed. Seed is sown
with a double disk seeder or the less satisfactory one-way disk at 7-8 kg per hectare.
Fertilizer requirements vary widely due to the sharply different soil types encountered in
rapeseed growing areas. Levels of macronutrients nitrogen, phosphorous and, in some
soils, sulphur are very low. Also lacking in some soils are the micronutrients manganese,
copper and boron. At harvest, a desiccant is applied and after the appropriate interval, the
crop is straight combined. The seed is normally artificially dried to less than 9% moisture
prior to storage or marketing.