As the canola crop nears the end of the growing season, signs of premature ripening are quite prominent. This year it might be easy to assume that soil moisture stress is the culprit. However, it is important to scout and take a closer look to determine what has happened in those areas. It might be moisture, but could also be disease or insect or fertility issues. Taking the time to assess the crop can help with future crop management decisions.
- Break open the stems of any bleached white plants and look for hard black sclerotia bodies forming inside the stem. High levels of sclerotia returned to the soil this fall can increase the risk of sclerotinia next year in canola and other susceptible crops such as sunflowers, field beans and lentils. If sclerotinia is present, assess the % of infected plants since half of this number will give a yield loss estimate. If fungicide was applied, evaluate that decision. Was a check strip used to determine if the disease was at least suppressed? Is it obvious infection occurred late in the flowering period, suggesting a later or split application may have been more effective? Was a fungicide not applied and perhaps should be under similar conditions in the future?
- Look for blackleg. Check for black rimmed stem lesions and basal stem cankers. If a high incidence (anything greater than 15% of plants) of blackleg is found, then this field should not be used in a tight rotation – consider rotations of one in three or one in four years. Also, the next time canola is planted on this field, ensure it is not the same variety, especially in tight rotations.
- Dig up some plants and check for galls from clubroot or root rot symptoms. If clubroot is confirmed, proper equipment sanitation to prevent spread will be critical. Click here for more on clubroot.
- Look for signs of insect damage that may indicate missed opportunities for control and a need for more thorough scouting in future years. Pod stripping and holes chewed in pods by bertha armyworm or diamondback moth larvae will be obvious. Less obvious are the tiny holes in pods and shriveled or devoured seeds beneath them, which suggest lygus bug and cabbage seedpod weevil feeding. Look for significant root maggot channels on the roots to determine if cultural control strategies should be considered in future years. Take note of fall flea beetle numbers. While high numbers in the fall do not always correlate with high numbers in the spring, these are the adults that will overwinter and emerge to feed on canola seedlings next year.
- Blank or missing pods are often found during this time. Click here to hear Murray Hartman, Oilseed Specialist with Alberta Agriculture and Rural Development, explain what causes this. Click here for a CCC factsheet.