Avoid swathing in the heat of the day to dodge green lock in canola

(Kara Oosterhuis/RealAgriculture)

With harvest underway and temperatures continuing to soar across the Prairie provinces, canola growers will want to weigh their options when it comes to when they swath — not only in the growing season, but on the day as well, to prevent green lock.

Doug Moisey of Pioneer Seeds Canada, says during the days where the daytime high is expected to reach 25 degrees C or above, producers should ideally only be out swathing when the temperatures are below that threshold.

“The concern is, especially when it starts getting above 25 Celsius, those plants are just not functioning. They’re not absorbing water, but when you’re swathing a crop down at 29 degrees Celsius, what’s typically happening is that you’re desiccating that stem and the plant itself cannot completely close their stomata openings, so they need a couple hours of shutdown time,” shares Moisey.

In these scenarios, Moisey advises growers to swath in the morning and later in the evening when the temperatures aren’t higher than 22 or 23 degrees. If producers swath perhaps too early, or during the heat of the day, they may see red seed as a result. He added anything that’s green and mushy has potential to shrivel up or lock in green and then if it does, he says it may be hard to keep it in the combine.

Check out a Canola School video on swathing in the heat

When it comes to this years’ canola crops, on top of the heat, Moisey says insects have done more damage in some areas than some producers think, particularly by lygus bugs.

“They were feeding quite heavily on pods as they were forming. When you open up some pods, I’m finding where you normally tend to 20 seeds in some locations, you’ve seen four or five. There’s a long pod there, but there’s no seed left. So, the heat has had a role, but insects have also played another role in this,” says Moisey.

As you move east, farmers in Manitoba have another concern: frost. However, Moisey says unless producers are starting to see temperatures drop to minus 5, there isn’t a significant need for concern.

“If it’s a standing crop and you’re 60 to 70 per cent whole plant colour change and if they are calling minus one, to me it’s a concern, but it’s not a concern. Just let it buck, let it fall through and what I tell guys is that if you can get eight to 10 hours at plus 14, plus 12, going on to plus eight, that canola crops actually hardened off during that time period. If that canopy is heavy enough, you’ll get still that underground protection,” explains Moisey.

Additionally, he says that if producers get a rain and then a frost, the rain can actually act as an insulator or blanket for the plant and essentially take the hit for the plant. Moisey also emphasizes the fact that canola crops need three good days prior to frost for it to dry down to prevent green seed.