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At harvest, look for late-season diseases and insect damage that can help with decision making next year.
—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 and a 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. A variety with maximum tolerance (‘R’ rated) should be selected next time if high incidence of blackleg is observed. Also consider a longer rotation — one year in 4 — for canola.
—Dig up some plants and check the roots 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 spring.
