Concerns about "stagey" canola crops during the 2009 growing season led many growers to consider the pod sealant products now coming to the Canadian market. Growers still wanting a clearer picture of sealants' potential effectiveness at the local level may want to plan ahead for smaller-scale tests on their 2010 crops.

Pod sealants are made from polymers that are purported to help seal canola seed pods and prevent them from splitting open in unfavourable conditions during the plants' ripening process.

"As with any new agronomic tool where information on its performance under our environmental conditions is limited, it is always a good strategy to start small in order to learn what works best," the Canola Council of Canada advises.

For an in-crop product such as a pod sealant, starting small may involve the use of check strips within a field.

In the case of a pod sealant, the council recommends that a grower trying the product leave both a swathed check strip and an untreated check strip of standing crop.

This way, the council suggests, a grower can first compare the yield he or she gets from a swathed, untreated crop against the yield from an untreated, straight-cut crop.

Then, he or she can compare the yields from both the swathed and straight-cut untreated checks against that of the sealant-treated crop.

"Comparing them both to the pod sealant will help assess potential yield benefits where (canola pod) shattering was minimal, and risk reduction where shattering was significant," the council said.

Transition

One Winnipeg distributor of a pine-based, food-grade polymer sealant recommends the product be applied by ground or air on canola crops when the earliest plants show a transition to ripening. Ideally, the company said, that would happen when the first pods in the field transition from dark green to light green.

A sealant then adds to the waxy layer on the outside of the plant, the company said. That in turn is meant to allow later-maturing plants in a "stagey" field to grow and ripen as well, rather than force the grower to terminate an entire crop before its time by swathing.

"The information provided by the companies suggests that the majority of the pods should be changing colour from green to yellow, but the pods should still be pliable enough to fold over without splitting open," the council said.

"However, it will also be important for there to be enough seed colour change within the pods to allow curing and harvesting within the window of protection provided by the product you are using. The best advice is to consult with your company representative on the ideal timing for your fields."

Generally, the council said, growers applying these products will want to stick with the high water volumes recommended by the company. The products form a physical coating to seal the pods against splitting open, so thorough coverage of all the pods is "very important."

The Winnipeg distributor, for one, says its product is then effective for 40 days after application. It doesn't claim the product will eliminate pod shatter entirely, but said it will allows the canola plant and pod to continue to ripen by allowing moisture out of, but not into, the pod.

The sealant's protective layer is also expected to stretch as the pod expands, the company said.