Questions of the Week

How to seed canola to reduce flea beetle risk? 

Flea beetles increase their activity once air temperatures reach 15°C. They will emerge from hibernation hungry. To reduce the risk of flea beetle damage, seedlings should reach the 3-4 leaf stage within a seed treatment’s three-to-four-week window of protection. “The clock starts ticking the day you seed,” reminds Manitoba Agriculture entomologist John Gavloski. To help seedlings germinate and emerge quickly, he recommends that, if practical, one wait to seed until soil is adequately warm for quick germination and early growth, and seed as shallowly as moisture will allow. Higher seeding and emergence rates can help dilute the damage per plant. Be aware of the updated label restrictions for lambda-cyhalothrin foliar insecticides and learn about alternative products here(Flea beetles: important tips of best management) (Canola seed treatments) (How to assess leaf area loss from flea beetles)

What factors determine the safety of seed-placed fertilizer? 

Ammonia-based fertilizers placed too close to the seed can be toxic to seed and seedlings, while nitrate and potassium-based fertilizers can cause salt-effect desiccation. Risk is dependent on rate and source, and increases in lighter, sandier, higher pH, and/or drier soils. Risk also increases with lower seed bed utilization: a smaller opener on wider centres concentrates the fertilizer in a narrow, more potentially damaging band.

To protect germinating and emerging seedlings, it is safest to apply no fertilizer in the seedrow. The only exception is phosphorus, which can safely be applied in-row at a starter rate (typically up to 20lbs/ac of P2O5) and can provide an establishment benefit for canola seedlings, especially in cool soils.  Always confirm the safety of seed-placed fertility. Simply turn off seedrow fertilizing for 100 feet, mark the location, then conduct plant counts in early season to compare treated and untreated strips. Noticeably better growth in non-fertilized test strips indicates damage and the need to re-confirm safe rates. (Right rates for seed-placed fertilizer) (Reducing toxicity of seed-placed phosphorus fertilizer in canola)

How to kick off the year with low weed competition, especially from herbicide-resistant kochia?  

Weeds are coming! Effective early season weed management is one of the most important keys to a successful crop. In fact, research from Saskatchewan shows pre-seed weed control was more important to yield than early seeding in wheat.  

Now is a unique opportunity to get control of glyphosate-resistant kochia. Scout: glyphosate-resistant kochia is becoming notably more widespread in areas where it hasn’t traditionally existed. Always opt for a tank-mix partner alongside pre-seed glyphosate to control resistant kochia. Certain herbicides, especially glyphosate and diquat (Reglone and others), are very dust sensitive. Here are top tips for achieving strong weed control in dry, dusty conditions. (Seed first or spray weeds) (Weed management – timing)

What herbicide carryover scenarios should growers watch for in 2023? 

The breakdown of residual herbicides does not always occur according to the timelines expected. Breakdown timing is influenced by soil’s texture, organic matter level, pH, temperature and – most importantly – moisture level. In dry conditions, breakdown slows, increasing risk in a future year(s). 

Herbicide carryover injury in canola can occur from even mild soil exposure to certain Group-2, 4, 5 and 15 herbicides. Canola (except Clearfield) is extremely sensitive to – and most at risk from – Group-2 carryover. Carryover injury can cause delayed maturity and losses from mild to total crop failure. To protect against herbicide carryover, double check previous years’ rotation and herbicide records, especially in cases of last-minute rotation changes. (Dry conditions elevate herbicide carryover risk) (Herbicide rotation and residues) (Scenario-specific options will improve herbicide-resistant weed management)