Alternaria has infected the pods of many hailed crops. Keep watching these crops. When infected areas make up 50% or more of the crop, swathing early may be the best way to salvage the yield in those infected plants if a large proportion of pod surfaces are covered with the black spots. Read more to see photos of alternaria infection.
Growers are encouraged to examine strange disease patterns to see if clubroot has arrived on their farms.
Growers seeing stem lesions or pre-mature ripening should take a closer to identify the cause. There is a good chance it’s sclerotinia. But it could be blackleg. It’s important to identify the cause because it will help in management for next year.
The sclerotinia spray decision is more complicated for growers with canola stands that are thin, late or at multiple stages. Multi-stage and thin crops that have good yield potential and are fairly well advanced may benefit from a split fungicide application.
Regrowth after hail may extend the flowering period, which also increases the sclerotinia stem rot risk. If yield potential is still high and if conditions favorable to sclerotinia stem rot persist, then a fungicide spray may pay off.
Small and vulnerable canola plants face many threats during their first three weeks. The crop may need your protection to get through these stages with its top-end yield potential intact. Canola growers are encouraged to walk their fields a couple times a week — or more — until plants are firmly established and growing strong.
Canola is most fragile during the first 21 days after emergence. The small plants are highly susceptible to flea beetles, cutworms, seedling diseases, weed competition and various other threats. Scouting may be required every day for at-risk crops, especially if a threat such as flea beetles seems to be building. At a minimum get out to each field a couple times per week during this period.
Fungicide to protect the crop from sclerotinia stem rot infection must be applied to petals before infected petals start to drop into the canopy. Petal drop starts after 30% flower, so the best time to apply is at or just prior to 30% flowering to cover as many flowers as possible. This is assuming conditions have been suitable for spore …