Canola seeding in mid May will have similar yield potential as canola seeded early May, according to Manitoba Crop Insurance data. (See the table.) Yield potential tends to drop off with late May and early June seeding dates. At those seeding dates, it will be important to look at factors that can delay maturity and increase the potential for yield and quality — green seed — losses.
Here are some factors that can delay maturity:
Low seeding rates. With fewer plants per square foot, these plants will branch more to compensate. Thin uniform stands can yield fairly well in a long season, but these side branches take longer to mature. In a shortened season, fewer plants per square foot will increase the risk of yield and quality losses.
Deep seeding delays emergence which pushes back the harvest window.
Non uniform plant stands. This can result from seeding issues, diseases, flea beetles, cutworms, etc. Accuracy in seed placement and scouting can ensure that pests do not cause stand thinning than can delay maturity.
High nitrogen rates. Canola plants with a good supply of nitrogen tend to stay vegetative for longer, maturing later. Pushing fertilizer rates beyond recommendations can increase the green seed risk in later-seeded crops.
Fertilizer placement. 20 lb./ac. of seed-placed phosphate fertilizer can help with pop up in cool soils. Rates could go as high as 40 lb./ac. with good soil moisture and a high seed-bed utilization (SBU). However, high rates of seed placed nitrogen and sulphate can set back seedlings. Putting non-phosphate fertilizer in a band near the seed will provide the nutrients needed for rapid growth once the plants are established.
Fertility balance in general. Low S can push the flowering stage longer.
Spraying off label. Spraying the matching herbicide after the label window may set back the crop and delay maturity.
Variety selection. Days to maturity from variety to variety can vary by a few days. Changing seed at this stage of the season is often difficult in large quantities, so growers with a longer-maturing variety may want to adjust other factors to reduce actual days to maturity. Use www.canolaperformancetrials.ca data to compare maturity ratings for varieties in the trials.