Don’t rush into frost protection strategies: CCC

Options seem to abound for canola growers wanting to rescue a viable crop from frost, but farmers should explore those options carefully before rushing into the field, the Canola Council of Canada warns.

For example, growers may be tempted to swath just before a frost hits, but that’s “generally not a good strategy” unless the crop’s seed colour has adequately changed, the council said in its newsletter Wednesday.

In order for a swathed crop to be protected from a frost, it must have been swathed long enough for sufficient dry down to occur prior to the frost event — typically at least three full days, the council said. Swathing too early can often translate into yield and quality losses.

Farmers are also advised not to use plant or pod colour to gauge proper timing for swathing, because some pods will appear ripe on the outside before the seeds are mature, the council said. Some varieties will show pod colour change long before the seeds do, while the opposite is true of other varieties.

This year, the council said, “significant” yield could be contributed by side branches, so seed colour change needs to be scouted on the side branches, not just the main stem.

Farmers will want to open up pods and look at the colour of the seeds to accurately assess swathing timing. Research indicates that the optimum stage to swath for both yield and quality is up to an average of 60 per cent seed colour change (SCC).

Uneven maturity

That said, where a farmers is faced with uneven maturity within fields, it might not be possible to swath all the crop in the 50-60 per cent SCC window.

In such cases, the best approach is to swath when the most mature plants are close to 60 per cent SCC, provided that the least mature plants are showing some seed colour change at the base of the main stem and that seeds in the upper pods (and branches) are dark green and firm.

That will keep the yield loss from seed shrinkage to a minimum and improve the odds that the seed will cure, though it’ll likely take longer and may require some more moist conditions, the council said. Swathing prior to 15 to 20 per cent seed colour change will likely reduce some yield potential, and could contribute to green seed issues under hot and/or dry conditions.

The council on Wednesday reported that its agronomists are starting to field a number of calls about how to hasten maturity of late canola plants within a field. Uneven fields are not good candidates for straight cutting, the council said.

Applying desiccant to an uneven crop will still leave too much green material and this material can cause “significant problems” in storage, the council warned. “With the ‘stagey’ crops this year, cutting may be the best option to even out maturity.”


Council staff note that with crops’ uneven maturity posing a problem in many areas, they’re also fielding questions about the benefits of pod sealant, a product designed to reduce shattering losses by preventing the pods from splitting open during ripening.

Pod sealants are “relatively new” in Canada, the council said, and “limited” scientific research has been done with these products under Prairie growing conditions.

With that in mind, a grower who wants to try a new product may do well to start small in order to learn what works best, the council said. Part of this learning should involve leaving check strips of an untreated area.

Of the questions fielded by council staff, most have focused on the timing of application for the sealant. Information from the sealants’ manufacturers suggests 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.

“It is still 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 council noted, urging farmers to consult with product representatives on the ideal application timing for their fields.

One other general tip that applies to these products is to stick with the high water volumes recommended by the manufacturer, the council said. Thorough coverage of all pods is important, as the products form a physical coating to seal the pods.

Other products

The council also noted that “a number of products” are being marketed to help boost canola crops’ protection from stresses such as frost. Council agronomists said they’re not aware of any scientific research in Western Canada to support such claims.

Growers who are considering applying a product for such a purpose are encouraged to ask for scientific research data to help with decision-making.

As with the use of any other new product, the council said, farmers should start small on a limited number of acres and keep an untreated check strip for comparison.

Finished flowering

Right now, the Prairie canola crop is generally finished flowering, with earliest fields generally having about 10 to 20 per cent colour change.

Swathing is just beginning in the very earliest fields that are reaching 30 to 40 per cent colour change in southwestern Manitoba and Saskatchewan, the council said.

Southern regions are about a week to 10 days away before swathing becomes general and northern regions are about two or three weeks away, the council said Wednesday.

In any case, all regions still need significant heat to hasten crop maturity.

“The absence of the first significant fall frost until at least mid- to late September is also important,” the council said.

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