Glacier FarmMedia – While it’s not as prevalent as the flea beetle, in a bad year, the aster leafhopper can cause significant yield losses for canola growers.
However, it reduces yields not by feeding damage but by spreading the bacterial disease aster yellows.
“Aster yellows is a disease that makes yellow things green,” Tyler Wist, a research scientist specializing in field crop entomology with Agriculture Canada in Saskatoon, said at Manitoba Ag Days 2025 in Brandon.
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The disease is not specific to canola. It can infect many grasses and broadleaf plants. However, in canola it can have a devastating effect on pod development. Instead of the standard canola pod, the pods are like large green bladders.
“If we cut them open, all the seeds have turned into tiny little leaf-like things,” said Wist.
It could mean complete yield loss in that plant if it was infected early enough, he added.
Most years, the incidence rate is less than 0.1 per cent incidence, but in 2012, there was a serious outbreak of aster yellows on the Canadian Prairies. That infestation saw incidences of five to 64 per cent in fields and caused an estimated $400 million in canola losses.
“That’s the one everyone remembers,” said Wist, but he added that 2023 saw incidences as high as 36 per cent.
Interestingly, there is a correlation between drought in the areas where they breed (in the Great Plains around Nebraska and South Dakota) and the level of infection we get up here in Canada.
Wist said the leafhopper feeds on wheat and barley in the United States, which typically wouldn’t mean a bad outbreak in Canada. However, if there is a drought in the U.S., the bugs will feed on weeds and pick up the bacterial infection and then float on the winds to infect crops in Canada.
