Yield and quality benefit from leaving canola standing longer before swathing. The common recommendation is to wait until at least 50-60% seed colour change (SCC) on the main stem. But that may be overly simplistic — especially if plant populations are low. The graph shows that as plant populations drop, more and more yield will come from side branches.
One step is to sharpen chopper blades to improve residue management, especially for fields in cereals now that will be in canola next year.
Check patches of pre-mature ripened canola to identify the cause. It could be blackleg, clubroot, sclerotinia stem rot (pictured) or something else entirely. Here’s how to identify the major diseases of canola as fields get close to swathing stage…
Glyphosate is registered for pre-harvest perennial weed control in canola. Glyphosate is to be applied when the majority of seeds are yellow to brown in colour and seed moisture is less than 30%. Heat fits between glyphosate and Reglone on the speed of dry down spectrum. Reglone is a contact herbicide (only kills what it contacts) and is registered in canola to dry immature green material to facilitate harvest. Reglone shuts the plant down quickly and basically STOPS it from maturing, which can lock in high green seed levels if applied prematurely.
In dry conditions: Threshold tables for lygus indicate that if canola is $12 per bushel and spray costs $8 per acre, the threshold at the early pod stage is 5 lygus adults or late instar nymphs per 10 sweeps (0.5 per sweep).
In moist and high-yield conditions: The economic threshold is likely quite a bit higher. At early pod stage, the lowest action threshold to consider in good growing conditions could be 10-20 per 10 sweeps (1-2/sweep). At thelate pod stage, 50 lygus per 10 sweeps (5 per sweep) at could cause a 2 bu./ac. reduction in yield — which could be a more suitable economic threshold in this situation.
Aster yellows is a phytoplasma infection that causes misshapen pods and flower buds. Most fields in most years have less than 1% infection, which is not an economic level of loss.
With severe hail after flowering, plants can start to regrow, going through flowering stages again. This really sets back maturity, but with enough time, new branches can produce enough yield to make harvesting worthwhile. The question is, is this a crop worth much more investment?
The Saskatchewan Ministry of Agriculture is planning its annual canola disease survey. Part of the survey involves soil sampling and DNA-based testing for the presence of the clubroot causal agent. The DNA test detects the clubroot pathogen at levels lower than those required to cause visible symptoms in the field, thereby providing an early assessment of disease risk before yield loss due to the disease occurs. If you would like a field tested for clubroot as part of the Ministry’s survey please email [email protected] with your name, phone number, RM and Legal Land Location.
MARA in Fort Vermilion Aug 5; John Guelly’s crop walk near Westlock Aug 10; canolaPALOOZA pre-harvest site tour in Lacombe Aug 15
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