BROOKS, Alta. — Five different pathotypes of clubroot have been identified in canola as research continues into the parasitic root disease and its spread.
And as it continues, four companies — Bayer, DL Seeds, Monsanto and Pioneer Hi-Bred — have bred 11 different clubroot resistant canola varieties with interim or full registration.
New varieties have curbed some of the worry about clubroot, which can spread easily in soil stuck to farm equipment, vehicles, animals and people.
Yet the characteristic clubroot galls, the bulbous growths found on the roots of infected plants, can still be found on resistant plants.
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Variety resistance is getting more specific on crop disease pathogens, but that information must be conveyed in a way that actually helps producers make rotation decisions.
Ralph Lange, researcher with Alberta Innovates Technology Futures, said that might cause producers to panic, but it isn’t a big deal in terms of disease spread.
“You will have some plants in there that form galls,” Lange told those on a tour of the clubroot disease nursery near Brooks.
Clubroot resistant varieties are hybrids and one line in the cross may not be resistant. While some plants may show symptoms, it’s unlikely to affect overall yield.
Similarly, he said galls on volunteer canola should not be cause for alarm.
In Europe, where clubroot has long been a problem, Lange said producers try to limit use of resistant varieties in fields known to have clubroot because resistance is showing signs of breakdown.
However, he said varieties have been tested out to five generations in Canada and it appears that breakdown is slow. Clubroot can also infect wild mustard, stinkweed, shepherd’s purse and flixweed, and has done so in test plots.
“I suspect that the stinkweed was a significant reservoir for the disease, because this pathotype here seems to really cause huge galls on stinkweed,” said Alberta Agriculture plant path-ologist Michael Harding.
Test plots also include cruciferous vegetables: broccoli, cauliflower, kale, kohlrabi, cabbage, Chinese cabbage, rutabaga and radish.
Clubroot inoculum is being deliberately cultivated at the disease nursery for collection and use in future greenhouse and growth chamber research.
It is made possible courtesy of the Lathom Hutterite colony, which bought the land about 15 years ago. Clubroot appeared the first time they planted canola, said Harding, indicating the inoculum was already present.
“So far they’ve managed to keep it contained through sanitizing and not moving contaminated soil to new sites.”
The colony grows canola no more than once every four years and avoids other susceptible crops.
“This land here is kind of marginal and so I don’t think they feel a lot of pressure to be in canola every other year here,” Harding said.
Clubroot has not spread anywhere else in the County of Newell, which surrounds Brooks. The county does an annual survey of canola fields to check for infection.
