Questions of the Week

Why is my canola yellowing early?

There are many reasons canola plants may turn colour prematurely. Is it clubroot / verticillium / sclerotinia / sunscald? Do not confuse early yellowing / purpling with the crop being ready to swath. While general disease scouting should be done at 60% seed colour change, investigate discolouring patches as soon as they appear for easier identification. Click here for disease ID tips for pre-harvest scouting.

Is your swathing plan ready?

Canola is not yet ready to swath, but now is the time to finalise the swath or straight cut decision. Do not swath too early: correct swath timing is a major contributor to yield. If the crop was battered by hail or wind, swathing may be better than straight cutting.

Now is also the time to make plans for effective scouting and harvest assessment at swathing. Put your scouting toolkit including clippers into the swather now so they’re readily available once the machine starts rolling. Swath timing is ideal for assessing multiple diseases; however, scouting at swathing should encompass more than just disease assessment. How are plant counts? What pest pressures exist? Are losses to shatter high at swathing? If the crop doesn’t appear that it will meet yield expectations, ask: what went wrong?

How to manage diamondback moth?

Diamondback moth numbers are rising in some areas, with multiple fields now exceeding economic thresholds. If diamondback moths exceed threshold and a second pest species (ex: grasshoppers) is present too, do not wait for the second pest’s population to rise before applying pesticide. Once threshold is reached on any one pest, spray. Choose your insecticide carefully: the window between spraying and swathing is shrinking quickly so doublecheck pre-harvest intervals before applying any product. 

What is the outlook for aster yellows?

There is much interest in aster yellows as risk appears higher this year than anytime since 2012. Some aster yellows is being reported. At this point, it is mostly cosmetic and not robbing significant yield. It is difficult to predict whether this will change. Aster yellows typically shows with highly visible symptoms, but in some cases can impact seed production without obvious outward evidence. Unfortunately, there are no control methods available. If you would like more information on testing leafhoppers for aster yellows, email AAFC Field Crop Entomologist Tyler Wist. 

How to assess maturity in uneven fields?

Uneven emergence and challenging growing conditions mean plant staging is patchy and/or variable in many canola fields. Maximizing profitability depends on accurately assessing maturity and determining where the bulk of the yield will be. Refer to the Canola Council of Canada’s Canola Swathing Guide for tips on how to assess an uneven field. (What to do with uneven fields) (Harvest management – timing, quality and yield)