Test your diamondback management skills with these four questions…
Diamondback moth larvae have been found in canola fields across the Prairies this year. Of those fields with the larvae, counts in many (perhaps most) are below and often well below thresholds. Some fields are at thresholds. Some fields seem to be well above thresholds. The key is to the check each field. Diamondback larvae can vary in number from field to field and even within areas of a field. (Photo credit: John Gavloski)
Here are answers to common questions….
Bertha armyworm adult moth counts were generally low across the Prairies in 2017. A few trap sites did enter the moderate risk level, but none was high. However, as experienced with diamondback moth trap counts this year, egg survival could be higher in dry conditions and warm weather will promote rapid growth.
In dry conditions, existing lygus threshold tables are still appropriate when making spray decisions. These tables indicate that if canola at the pod ripening stage is $12 per bushel and spray costs $12 per acre, the threshold is 11 lygus adults or late instar nymphs per 10 sweeps (~1 per sweep).
Butterflies have siphoning mouth parts, much like a straw. They are harmless to crops and may actually provide some pollination benefit. Butterfly larvae from these three species will feed on crops, but are not major pests of canola and rarely cause enough damage to warrant a spray.
The later hail occurs in the season, the more damage it can do to yield. While canola can keep flowering to compensate from hail that occurs during flowering, hail at the late pod stage can result in unrecoverable yield loss.
Optimal swath timing for canola yield and quality is when at least 60% of seeds on the main stem are showing some colour change. Seed colour change (SCC) is considered any amount of yellow or brown on the seed. (See scouting tips below.) This increases crop yield because side branches have longer to fill and average seed size for the whole plant is larger.
Here are 10 things to think about and get tuned up in preparation for harvest:
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