Many growers who have tried straight combining canola often see no clear advantage or disadvantage when it comes to yield. The value of eliminating the swathing step is enough for many, even if it means an added step to apply a harvest aid such as glyphosate, Heat or Reglone. Some growers straight combine only a few of their crops, keeping the swather for higher risk fields.
Overall, it seems now that canola growers are more comfortable with the idea of straight combining, even if most have not tried it yet. New varieties with reduced pod shatter have helped.
This article looks at situations where swathing may still have an advantage over straight combining. Thank you to those who responded to our tweet.
1. Lodged crop. Lodged canola crop may not dry down enough for efficient straight combining, and swathing should reduce the risk of putting a rock through the combine while trying to pick crop off the ground.
2. Precipitation — hail, snow, extended rain. Hail tends to cause higher shatter losses on standing canola versus swathed canola. The challenge here is that hail cannot be predicted ahead of time. After hail has gone through, growers may choose to swath the crop — even if it’s close to straight combining stage — to limit losses from hail-weakened pods. (Note: Canola swathed after a hail will still be at risk of losses if hail-weakened pods pop open in the swath or as the swaths are picked up.) Heavy snow can be worse on standing crop, pushing it down and making it difficult to pick up. Snow is easier to forecast than hail, so if snow is coming, consider swathing standing crop, even if late. Extended rains can also increase the risk with standing crop, and soften pods can peel open.
3. Wind. Wind tends to increase the shattering risk more for standing crop than swathed crop. Varieties with higher tolerance for pod shatter help reduce the wind risk. Swathed crop can also roll in heavy winds, so swathing is not without its wind risk.
4. Frost. Through Twitter, one grower asked for comments on leaving canola standing through frost events prior to harvest. This grower lost 15 bu./ac. leaving frosted canola standing in 2014. IHARF responded with: “Typically see high losses on standing canola if touched by frost when still green. Probably always better to swath froze canola.” But check frost severity. Early swathing can be costly.
5. Unsuitable variety. Some varieties are better than others when it comes to holding on to pods and pod shatter tolerance. Certain varieties are just not well suited to straight combining, and neighbours or agronomists with straight cutting experience will be able to tell you which ones are better to swath. IHARF study.
6. Late crop. Canola left for straight combining can take a little longer to be harvest ready. Experienced growers say 5 to 10 days later, in some cases. For that reason, swathing may be the better option for very late crops.
7. Combine power and reliability. Canola plants left for straight combining do not dry down as much as swathed plants, and this green material will require higher combine horsepower to harvest efficiently. Older combines with lower horsepower may not be well suited to handle tough canola stems, especially in a thick high-yielding crop. On reliability: Combine breakdowns are more stressful with standing canola. Canola left for straight combining has a small window where harvest timing is ideal. When it’s ready, you need to go. If the combine happens to break down at that time, the delay could present a higher risk of yield loss. Swathed crop provides much more flexibility when it comes to combine timing.
8. Combine header. Studies show that all straight cut headers can work in canola. The advantage goes to variable headers with the cutter bar that moves out in front of the reel to catch canola shelled on impact. With draper headers, the key it to have pea augers installed to guide crop into the feederhouse.
9. Harvest logistics. Growers may find that a combination of swathing for late or uneven crop and straight combining for even ideal crops helps keep harvest moving efficiently. Straight combining late green crops in cool conditions can be a slow process. Look at the number of canola acres to harvest, the staging of the crop and whether it can be combined in a timely matter if all of it were left standing.
10. Disease. Alternaria can spread faster in green standing crop, while swathing tends to stop its progress. Crops heavily infested with sclerotinia stem rot may not benefit from being left standing, especially with their weakened stems, however sclerotinia can spread in the swath. In general, swathing is often the better alternative in heavily diseased crop.
11. Not desiccating. (Yep, this Top 10 is a Top 11) It can be difficult to achieve an acceptable level of loss if the crop material is very green and not breaking up well through the combine. Losses can vary substantially, and can be high when slowing down in very green areas. Swathing may provide an advantage in weedy or uneven crops without a pre-harvest application.
Source : AlbertaCanola