Questions of the Week

What’s crawling /flying in that field?

Cutworms are being reported in multiple areas. Many reports are from fields with uneven growth stages and/or poor emergence, likely because fields with issues are being more intensively scouted. Expect cutworms anywhere. Refer to this guide to identify species, as different species emerge at different times and may require different management. Alberta offers a cutworm reporting form and mapping tool. In Saskatchewan, please report cutworm findings to Saskatchewan Ministry of Agriculture entomologist James Tansey. In Manitoba, report to Manitoba Agriculture, Food and Rural Affairs entomologist John Gavloski.

Flea beetles are appearing in pockets. In areas where the crop is not stressed, canola should outgrow risk quickly. In dry areas, the crop may stall and could require more intensive flea beetle management, especially if the three- to four-week seed treatment protection window closes while the crop is still vulnerable. This early in the season, the crop should be visibly growing and improving from day to day. The respraying program and product performance deadlines for flea beetles are available in this week’s Community Connections. (Flea beetle findings that shape management choices)

Diamondback moths are being reported, mostly in southern Alberta and at several locations in Saskatchewan. While this first flush of moths likely won’t cause much damage, they could be a precursor of a later, more destructive generation. Scout.  

Unsure about an insect’s identification? Refer to this guide. Before considering insecticide, ask: is the problem actually what I think it is? Assess all potential causes for poor establishment.

Best steps for tackling weeds? 

Weeds are growing quickly now. To manage them effectively:

1. Don’t wait. Early is always best for managing weeds.

2. Scout to determine specific target species, then choose tank mix partners (ensuring compatibility) and adjust rates to suit targets. Spray ‘recipes’ are available here.

3. Strive for a highly effective first pass, even if the plan is to get back in for a second pass. 

4. Remember that adequate, high quality water is the cheapest factor towards improving a herbicide application’s control. 

5. Manage hard water for the best efficacy of both glyphosate and glufosinate. Ammonium sulphate is an inexpensive additive that can stop minerals from tying up glyphosate/glufosinate molecules. (Water quality and herbicides)  

6. Consider temperature at application: Liberty is effective in heat but anything above 30°C is too hot for a systemic.  

7. Always follow labels.  

Why are early season plant counts so important?  

The 3-leaf growth stage is the ideal time to calculate emergence and assess seeder and seeding performance. Remember: the number of plants per square foot is less important than growth stage uniformity. If emerging canola shows inconsistent growth stages, be a detective (hint: of the many reasons for poor establishment, straw management and seeder issues are the most common). Keep good records of emergence and uniformity (or ask your agronomist for help with this valuable task) to optimize seeding next year.   

Inconsistent growth stages now are not the end of the world, especially when early season growing conditions are favourable. However, variability at emergence could influence later season sclerotinia spray decisions. Consider: if the crop does not even out over time, what portion will produce the majority of the yield? (Missing plants – what’s the cause) (Canola Calculator) (Plant populations: How to count? Why low?)

Add more N because increasingly optimistic?

Recent rains in some areas have some growers hoping for better yield than they might previously have anticipated. Adding nitrogen will offer more ROI than adding other nutrients at this stage in the season but must be applied before 6-leaf. Ask: what is the revised yield target? Does the crop have enough nitrogen to achieve that target? One bushel of canola requires approximately 2.5 to 3.0 pounds of nitrogen. Sulphur deficiencies can still be corrected where necessary up to the early flowering stage. (Tips to apply nitrogen and sulphur in season) (Equipment for top dressing fertilizer)
 
In warm, moist conditions, top-dressed nitrogen is at risk of high losses. Protect the nitrogen source. A urease inhibitor will protect applied nitrogen from gassing off until rain can move that nitrogen into the root zone. If going into saturated soil, a nitrification inhibitor will reduce nitrous oxide emissions and leaching. However, a dual inhibitor is not always necessary.  

Micronutrients are unlikely to offer ROI, except where tissue and/or soil tests indicate a deficiency. Warm temperatures and adequate moisture mean more mineralization and greater plant-availability of all nutrients.