Questions of the Week

How much yield will blackleg infection cost?

It is increasingly clear that blackleg will be a significant burden across the Prairies this year, including in fields that have not faced the disease before. Blackleg in canola can cause yield and quality losses, impact profitability and may cause market risk. Use the CCC blackleg loss calculator to estimate yield and dollar losses per field based on a simple 0-5 visual disease severity rating. While nothing can be done at this stage in the season to manage blackleg, start planning now to reduce loss in future years. Scout diligently now through harvest. If blackleg’s characteristic black ‘specks’ (fungal fruiting structures) are found, send samples for race identification (a list of labs is available here). Any field with prior blackleg infection should only be planted to a variety with an R-gene resistant for that specific race. Opt into blackleg seed treatment. (Five tips for managing blackleg) (Basics of blackleg management) (Canola Encyclopedia: blackleg)

How long between spray and swath?

Pre-harvest intervals — the number of days between a pesticide/desiccant application and swathing/straight cutting — varies from 1 to 60 days depending on the product. Always double-check the pre-harvest interval, especially if applying a new product or changing plans late in the season, as cutting too soon after application can make a crop unmarketable. In combination with the product label, refer to Keep it Clean’s Pre-harvest Interval Calculator before any pre-harvest spraying. The calculator can be used in two ways:

1. To check a pre-harvest interval timeline: choose the crop type and the intended product to calculate how many days must pass between application and cutting the crop.
2. To choose a product: choose the crop type and pesticide category, then an intended number of days to crop cutting. The calculator will offer a list of products that fit into that window (if any exist). 

How to prep now for success next year?

Now that harvest is underway for many pulse and cereal crops, remember: next year’s canola stand establishment starts now. Is what’s coming out of the back of the combine going to help or hamper the next crop? Choose a stubble height that is high enough to capture snow but low enough not to interfere with seeding. If post-harvest weed control will be needed, leave enough leaves on weeds like Canada thistle to achieve an acceptable kill. Ideally, well-managed residue won’t require a heavy harrow pass. Start planning now for next year’s seed selection: what pest / disease / etc. challenges could seed selection help mitigate? While it’s still a little early for fall soil sampling (best once soil has cooled below 10°C), take note of field variability now to help guide sampling later. Use yield monitor information as a scorecard at the end of the season, calculating how much it cost to grow each bushel to determine profitability of each acre and what needs to change next year. (Effect of cereal crop residue distribution on the following year’s canola emergence and yield) (Manage residue with the combine alone)

How much does swath timing really matter?

Waiting to swath until at least 60% of seeds have changed colour is one of a canola season’s lowest input, highest return management choices. Note: pod colour change is not a clear indicator of seed colour change, especially since sunscald can make the outside of a pod look more mature than it really is. Always open pods, using this guide to assess the seeds themselves. Factor in side branch maturity too, especially on plants where the yield is spread between the main raceme and side branches. (Swath timing, quality and yield)