Uneven Canola — When to Make the Harvest Decision

by | Aug 31, 2020 | Agronomy Solutions

Some canola harvest has begun on the prairies, but for those still waiting to start, there are a few things to keep in mind, especially with stands of uneven canola. If you have two to three fields of canola with even maturity, it’s pretty easy to hit that optimum timing. But when you have multiple fields of different canola varieties, all in different stages, it can get tricky.

It all starts with walking your fields. Go into the early maturing areas of your fields, and into the later maturity areas. Assess for 60 per cent seed colour change (SCC) on the main raceme (30 per cent moisture, physiological maturity) in both areas and know where the majority of yield is going to be coming from in that field. Remember, if there is a speck of brown/black on a green seed, it is considered to have changed colour.

If the majority of the yield in the field is in your first stage, manage accordingly. If growing a variety with a harvest management or pod shatter trait, glyphosate application as a pre harvest aid (75-80 per cent SCC) or desiccant (90 per cent SCC) (Stage, Reglone)  gives you a little bit more leeway before harvest in comparison to swathing, allowing you to capture some yield  from the later maturing plants. These traits also help reduce shatter losses if swathing past 60 per cent SCC.

If the majority of your field is later maturing, you’ll likely incur some shatter losses as the earliest maturing plants dry down. This can be frustrating, but it is important to maximize the economic potential of the crop by waiting for the plants where the majority of the yield for the field will come from. Remember, desiccants dry down the plant, they do not enhance maturity. Once a desiccant or pre-harvest aid is sprayed, there won’t be any more seed colour change. If sprayed too early, higher green counts could result. If you are growing a variety with a harvest management or pod shatter trait, you have a bit more flexibility versus a variety that must be swathed.

When making the decision to use a desiccant or pre harvest aid, remember that environmental conditions will have an effect on their efficacy. In hot, dry conditions, diquats will work quickly, but in cool, wet conditions, you could be waiting upwards of two weeks. Pre-harvest glyphosate will work slower than diquats, even when supplemented with product such as saflufenacil (Heat). Regardless of product used, be sure to use the recommended rates of water to ensure optimum coverage.

When desiccating straight cut varieties, it must be done at the proper staging. The biggest thing to consider when you’re looking at desiccating is that you do have a preharvest interval for all products – with the world situation as it is right now, we have to be very careful about MRLs. If we’re using these desiccant products, we need to observe the preharvest interval to make sure we don’t have any issues once it’s in the bin and we’re trying to market it.

Overall, we can’t control the weather or the world markets, but you can control what’s going on in your field and you can control your harvesting – all we can do is have a plan in place. In variable staged canola fields, start walking your field about a week after flowering is complete and start developing a harvest plan. Whether 50 acres or 500, being ready to go at the right timing will allow you to maximize returns in challenging conditions.

Derek Flad

Manager of agronomic services for southern Alberta, Nutrien - Derek Flad is the manager of agronomic services for southern Alberta for Nutrien Ag Solutions. He holds a Masters of Science in Plant Science from the University of Alberta and a Bachelor of science in Agronomy from the University of Saskatchewan.