Scouting at swath timing is a good time of year to begin assessing the growing season and begin planning for next year. In Manitoba, earliest harvested fields are not yielding to expectations. Take this opportunity to try and identify what might be at play leading to disappointing yields. Mother Nature’s environmental challenges played an important role in many cases but are there other management factors that producers can influence? Have tight rotations led to an increase in disease? Was a soil test performed to ensure adequate fertility was available? Was emergence hampered by poor residue management or poor depth control at seeding? Good records allow for evaluating this season and for trying to make improvements going forward.
Where are the pods? This year it is quite common to find missing pods on the main stem and side branches across all regions. This shouldn’t be surprising, considering the growing conditions this year. Canola pod formation is somewhat finicky. When canola is grown under optimum conditions (ie. regulated conditions in a greenhouse), there are still about 20% of flowers that produce no pods, and it is typical that only half (50%) of canola flowers will result in a pod being formed under field conditions. Subsequently, it is not unusual for canola exposed to a number of external forces (ie. environmental stresses) under field conditions to have another 20% of flowers that do not produce pods. Canola can sometimes compensate for early aborted flowers by producing additional buds and flowers, but this ability depends on subsequent conditions. In the end, it is the number of pods per unit area and number of seeds per pod rather than the number of blanks that determine yield. However, a high number of blanks are definitely a sign that the crop has been under stress. The question to answer is could those stresses have been better managed?
Heat hurts canola. Canola is sensitive to high daytime and nighttime temperatures especially when it is in reproductive stages. Murray Hartman, Oilseed Specialist with Alberta Agriculture, advises that after 3 to 5 days of temperatures greater than 30 C canola begins to be stressed. If this prolonged heat arrives during flowering or early pod formation, then blank/sterile pods can result. If it occurs during ripening, smaller seed set will likely occur. Not only do high daytime temperatures affect canola, but high nighttime temperatures as well. When overnight temperatures exceed 16 C heat stress of canola is aggravated.