Straight Cut Or Swath Canola? Know Your Fields

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Straight cutting canola can improve yield and seed quality and it can be economical, but under the right conditions, says Tiffany Martinka, agronomy specialist for the Canola Council of Canada (CCC).

“Make the decision to straight cut over swathing after you have assessed canola fields individually,” says Martinka. “It’s all about minimizing losses due to pod shatter and drop. Anything that may have weakened the pods or petioles makes a canola crop a less than ideal candidate for straight cutting.”

The CCC advises to assess each crop carefully before choosing straight cutting, based on four factors:

Crop canopy – The crop should be well knitted and slightly lodged to reduce potential seed loss through pod shelling. If a large proportion of the plants appear to move independently in the wind, they will be at high risk for shattering as the plants senesce and dry down. The plant stand should be thick (hard to walk through). Pod integrity can be affected by frost, drought and insect damage. A uniform crop with minimal green weed growth is also a huge advantage when straight cutting.

Disease – The crop should be relatively free from blackleg, fusarium wilt, sclerotinia and alternaria, as these diseases can result in premature ripening, causing the crop to be prone to pod shatter.

Hail – Crops affected by hail are poor candidates for straight cutting because the physical damage reduces pod integrity and they normally see greater disease infection.

Frost risk – Canola seed is at significant risk for fall frost until moisture drops below 20 per cent. This drop will take much longer in a standing crop, so late-maturing crops are poor candidates for straight cutting. They will be much more vulnerable to yield loss and to downgrading from frost.

Short, severely lodged, or excessively branched canopies may be candidates as well, because if swathed there would be minimal stubble left to anchor the crop. In this situation growers should consider the potential for wind damage to the swath relative to shattering risk if left standing.

“Growers should also note that when trying pod sealants for the first time with straight combining, it is important to leave a check strip,” says Martinka. With check strips, producers are able to see whether a product was useful for them on that field, that year. Over time this information will help determine what crop conditions are most likely to benefit from an application.

TWO-WEEK DELAY

Timing of straight cutting is also an important consideration, says Martinka. “In order to get the proper seed moisture content, straight-cut harvest often requires a delay of two weeks or so relative to a swathed and combined canola crop. The crop should be harvested as soon as the seed moisture and percentage green seed have dropped to acceptable levels, in order to minimize the time the crop is susceptible to wind damage. The main stems will often still be retaining some green colour.”

Keep in mind that the distinctly green per cent cut-offs for No. 1, 2, and 3 Canada canola are two, six, and 20 per cent respectively.

Martinka also advises that reel and ground speed should be kept evenly matched when straight cutting. “Producers should consider cutting at an angle to the direction of lodging to minimize shelling losses that are caused by the header. Combining in this direction also helps canola to feed into the combine more smoothly, which helps reduce harvest losses.”

If straight cutting canola at seed moisture above 10 per cent as a strategy to reduce losses out in the field, growers are advised to have adequate bin space with aeration and/or drying capacity since safe storage will be an issue at higher seed moisture contents.

If considering straight cutting for the first time this year, growers are advised to start with a relatively small number of acres and build up from there in future years, says Martinka.

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