Wild radish infesting a conventional canola crop
Weed Control
Choose paddocks relatively free of broadleaf weeds especially charlock, wild turnip, wild radish and other weeds of the Brassica family, as in-crop herbicide options are very limited.
If canola is to be grown where these broadleaf weeds occur, use a triazine tolerant variety and spray either atrazine or simazine pre-emergent or atrazine post emergent.
Grass weeds can be readily controlled in canola using trifluralin or post-emergent herbicides.
When choosing paddocks for canola, be careful with those treated with residual herbicides especially Group B and triazine herbicides (for conventional varieties) as their residues can affect canola. Check labels for re-cropping intervals as some are up to 36 months.
Ensure all spray equipment is thoroughly decontaminated before using it to spray canola.
Use chlorine if the spraying equipment has previously been used to spray sulfonylureas, ammonia for hormone herbicides (salt and amine formulations) such as 2,4-D amine and MCPA and liquid alkali detergent for Broadstrike® and Eclipse® decontamination.
Where possible, use separate spraying equipment for residual herbicides such as the sulfonylureas. Imidazolinone tolerant varieties are marketed as Clearfield* canola. These varieties allow the use of the Group B herbicide On Duty® (Imazapic and Imazapry). Clearfield* varieties do not suffer from the yield and oil penalty which the triazine varieties exhibit. The use of Clearfield* varieties allows the rotation of herbicide groups and broadens the spectrum of weeds controlled.
Harvesting
Canola generally withstands extended wet harvest periods better than other crops such as wheat. However, severe windstorms can cause seed shatter more readily in canola, but newer varieties have been selected to improve this characteristic.
Harvesting Canola
Crops can be either windrowed or direct harvested. The method chosen depends on the availability and cost of contract windrowing, the type of harvesters available and the relative risk of adverse weather in a particular locality.
Some of the advantages of windrowing are: uniform ripening, earlier harvesting (7–10 days), less exposure to spring storms and rain, reduced shattering losses during harvest and less hail and wind losses. Harvesting can usually continue ‘around the clock’.
Windrowing should start when 40–60% of seeds have changed colour to red, brown or black. As the crop is usually ready for windrowing 20–30 days after the end of flowering, regularly check the crop for seed colour changes.
The end of flowering occurs when only about 10% of plants have any flowers left on them.Windrowed crops should be ready to harvest 5 to 14 days after windrowing depending on the weather. The moisture content of the grain should be 8% or less.
Direct harvesting is cheaper than windrowing and can be done with either an open-front with an extended platform or with a belt-front attachment. Canola is ready to harvest when nearly all the pods are dry and rattle when shaken, pods are pale brown and the seeds are dark brown to black and have less than 8% moisture content.
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