Questions of the Month

How to harvest green crop sooner and faster? 

Canola curing takes longer in cool, moist weather. Best to be patient. While pre-harvest sprays don’t work as well in cool weather, cool weather should bring a good killing frost (soon, we expect) that can speed along the dry down process and make the crop easier to combine. 

Can powdery mildew cause slow curing? Provincial plant pathologists say no.

• David Kaminski from Manitoba: “Powdery mildews (with the exception of those on cereals) thrive in dew-forming conditions – that is warmer, dry days followed by cool nights.”
• Michael Harding from Alberta: “One of the final symptoms of powdery mildew is premature yellowing and dropping of leaves. The opposite of extended greening. Powdery mildew won’t get any food when infecting a dying or dead plant, so we only see it sporulating on living, green host tissues.”
• Alireza Akhavan in Saskatchewan: “Yes, we have heard of powdery mildew cases in Saskatchewan and at least one very severe case.”

Tall crop and slow curing. Some farmers are reporting taller than usual canola plants. With slow curing crop, farms may want to cut higher to put less biomass through the combine. If swathing, perhaps don’t use the full width of the swather and cut higher to keep the windrows a little smaller for faster curing. 

Should canola regrowth get sprayed this fall? 

There is no clear answer. Winter should kill canola regrowth, so if that’s the only weed, you could consider saving money and not spraying. Regrowth is also like a cover crop, holding on to soil and providing some “green manure.” Granted, those nutrients may not be available to next year’s crop. On the other hand, canola regrowth is taking up moisture. It also creates residue that may need to be managed next spring if fallen stems are difficult to seed through. If you expect more weeks of growth this fall, management may be required. 

On the topic of fall spraying, does herbicide work better after a frost? No. While cooler temperatures with daytime highs in the mid to high teens do increase movement of sugar, and with it glyphosate, to the roots of perennial weeds like Canada thistle, frost does not enhance that movement. Fall weed control timing and targets. Note restrictions for herbicides sprayed this fall on fields planning for canola in 2024. Distinct, for example, should be sprayed before October 1.  

Is it time to switch blackleg R genes? 

Farm reports suggest higher levels of blackleg this year, with notable yield loss in some fields. If farmers are noticing an increase in blackleg symptoms, even if yield loss is not evident, switch to a new source of blackleg resistance the next time canola goes on that field. Stubble tests can identify blackleg pathotypes in a field and make recommendations on which R genes to use. (Manitoba testing program. SaskCanola testing program ends October 27.)

If the “blackleg” might be verticillium stripe, canola that is resistant to blackleg in a field is also known to reduce the incidence levels of verticillium stripe. Win-win. 

Disease resistance can be critical to canola success in terms of yield and profitability. Include the appropriate disease resistant traits when choosing the right cultivar for each field. 

Does fall harrowing make sense?  

Yes… 

• Heavy harrows can spread straw in the fall or early spring if combine performance was inadequate. This can make the seeding operation easier. 
• A light scratch in the fall can stimulate weed germination, including canola seeds that will become volunteers. The actual germination will likely vary significantly – zero per cent if soil is dry and no rain is received to 90+ per cent if conditions are perfect. 

No…

• Harrows can cause soil erosion and disturbance, which will degrade the seedbed and dry it out. Heavy harrows also disturb the standing stubble that reduces soil erosion and catches snow that contributes to soil moisture.
• Extra tall stubble increases crop yield. 

How much nutrient do I lose by baling cereal straw? 

Harvested seeds remove a lot of nutrients. Baling or burning does as well. Alberta Grains info on the nutrient value of cereal straw.

Dropping residue also means a concentrated layer of chaff the baler doesn’t pick up. This chaff can create challenges for crop emergence next year. These windrows are often visible as strips of poor emergence. Some harrowing to spread out these chaff strips may help with emergence. 

What is the right time for fall soil sampling? 

When using soil sampling to plan fertilizer rates for next year, the best time to sample is after soil has cooled to at least 10°C. Cool soils reduce the microbial activity that can mobilize nutrients. Soil samples collected after this activity slows down will more closely reflect spring nitrate contents.  

If farms plan to band fertilizer in the fall, plan to soil sample first, but wait until soil temperature is as close as possible to 10°C. This should allow for fall application that will be at lower risk of losses after soils have sufficiently cooled, before the ground freezes. 

If hiring someone to take soil samples, talk to that person now and get on their list. Canola 4R Advantage has funding available for soil sampling.