Topics for the Week

Late season disease scouting

It’s now time to begin looking for late season diseases. While watching for disease is easiest while spraying desiccant or swathing, make time to walk fields at least weekly from now through harvest as certain diseases (especially clubroot and blackleg) can progress very quickly. Symptoms will get more striking as the season progresses, but early identification allows for better pre-planning to mitigate spread at harvest.

Canola disease surveys will be underway within the next couple of weeks. We encourage growers and agronomists to sign up. Quality data helps paint an accurate picture of disease across the Prairies, informs next year’s disease forecasts, and shapes upcoming disease research. To participate in the Provincial disease surveys or to take advantage of free disease testing (which is not included in Provincial survey results), click here.

What’s chewing into your canola?

Insect management should be top of mind during canola flowering and podding. Scout carefully for lygus bugs and diamondback moths now: because these pests can achieve several generations within a single growing season, a small population today may precede a major issue two to three weeks from now. Reports of bertha armyworm have been low so far, but grasshoppers may be nearing threshold in some parts of the southern Prairies. When assessing insect feeding damage, ask: could it be hail bruise instead?

Remember: insecticide should ONLY be applied if the pest population exceeds its action threshold and should be timed around beneficial insects’ activity where possible. (Proper sweep net technique)

NDVI: scouting from the sky

Frequent and effective scouting is among the most critical crop management tools, but properly assessing large fields for diseases, pests and even swath timing can be challenging. Though no technology replaces boots on the ground, Normalized Difference Vegetation Index (NDVI) images – images taken by drone or satellite that indicate biomass and plant health – can offer insight into the crop and guide better ground truthing. Specifically, areas with higher crop density may correspond to higher disease risk (especially sclerotinia); stressed or weakened areas may be compromised by heavier than average disease or pest pressure. Keep in mind that canola’s yellow flowers can disrupt NDVI readings.

Statistics Canada uses NDVI for its Crop Condition Assessment here.

Managing glyphosate-resistant kochia

Glyphosate-resistant kochia is now found across all three Prairie provinces, even in the black soil zones. As kochia produces 15,000 or more seeds per plant, it is critical to manage glyphosate-resistant plants before they go to seed. Mowing small patches prior to seed-set (or hand-pulling if minimal spread has occurred) is generally the best mid-season management option. (Glyphosate resistance and integrated weed management)

Consider options now in case resistant plants are discovered closer to harvest. Do you have a desiccant / tank mix partner on-hand? What combining or swathing techniques (and equipment cleaning) might help minimize seed spread? Should cutting the infested area for silage be considered? (How to manage herbicide resistance in your fields) (The satisfying pulverization of weed seeds)  

Manitoba’s PSI lab offers a DNA test for glyphosate-resistant kochia. This video shows how to sample effectively.