Timing is key when windrowing canola
Windrowing canola is the preferred method for many growers in south-west Victoria compared with direct heading.
Canola is an indeterminate crop, meaning it will continue to flower until it is limited by an environmental factor such as temperature, water availability, or limited by nutrients. This flowering window can occur over a prolonged period which can mean the lower pods mature before the top pods.
A benefit to windrowing is it will naturally speed up the maturity of the crop, in some cases by up to 8-10 days, ensuring all pods are mature come harvest. This method can also minimise shattering of the lower pods that may have matured earlier. Windrowed canola can also be less susceptible to weather events such as rain, hail, and wind, however this can vary across paddocks and depend on the severity of the weather event. It can also provide more flexibility in time management for the grower, as the timing of harvest is not as critical.
While there are benefits to windrowing, the importance of windrowing at the optimum timing in canola is crucial to ensuring grain yield isn’t penalised. Some studies have found canola yield can be reduced by up to 30% where crops have been windrowed earlier than recommended.
The recommended level of seed colour change is 40-60%. When determining seed colour change in canola it is important to collect pod samples from different positions in the canopy, both brown pods from the base of the plant and green pods from the top of the canopy should be examined.
The easiest method to determine percentage of colour change is to shell the pods and place the seeds into a container. Then visually assess the percentage of seeds that have begun to change from green to red, brown, or black in colour. If it looks as though 40-60% of those seeds have changed, the crop will be in its optimum window to windrow. GRDC Grow Notes on canola have some good images on seed colour change and handy tips on windrowing for further reading.