Canola School: Aster Yellows: Why it's Best to Leave the Sprayer in the Shed


Two years ago if you had asked the average Saskatchewan canola grower what aster yellows was, they likely wouldn’t have been too concerned about it, if they had ever heard of it at all. That’s because aster yellows, a disease carried by the aster leafhopper insect that mangles the buds/pods of a plant, typically occurs at very low levels and random areas every year.

2012 was an anomaly, however, and farmers across all three Prairie Provinces, and especially Saskatchewan, were hard hit by the phytoplasma that deformed heads and knocked out serious yield. It’s understandable then that many farmers are watching still-flowering canola fields with baited breath, and many have been itching to bust out the sprayer at the first sign of the insect.

Not so fast, says Holly Derksen, field crop pathologist with Manitoba Agriculture, Food and Rural Initiatives. 2013 appears to be a much more normal year for the pest, and, though the leafhoppers have been found this year, they are later and in far lower numbers than last year. The phytoplasma is only a threat to the plant while the crop is flowering and developing pods — as crops move past flower, the yield hit drops dramatically even if the leafhopper appears. What’s more, even in high pressure or early appearance situations, spraying is rarely effective. Watch the video to find out why.


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