THURSDAY, MAY 1, 2014
VOL. 92 | NO. 18 | $4.25
Foreign labour GROWING WITH FARMERS FOR 90 YEARS
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The agriculture sector depends on it. | P. 4
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EVERYONE LOOK BUSY, HERE COMES THE BOSS
Wainani Englot wanders over to help Albert Walter, left, and her father, Steve Englot, as they get their equipment ready for spring seeding near Indian Head, Sask., April 21. | NICOLE DERKSON ENGLOT PHOTO
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CLUBROOT | RESISTANCE
Clubroot in resistant canola? Erosion of resistance? | Researchers don’t know if it is a new virulent phenotype of clubroot BY MARY MACARTHUR CAMROSE BUREAU
The discovery of a possible new strain of clubroot in two fields in the Edmonton area is raising concerns that resistance is already breaking down in new clubroot resistant canola varieties. Stephen Strelkov, a plant pathologist with the University of Alberta, said clubroot galls collected from fields in the Edmonton area and regrown and tested in the greenhouse are raising concern about a new virulent phenotype of clubroot. “There were a couple cases where there actually was increased infectivity by those strains in the greenhouse conditions. It did suggest it was a new
virulent phenotype,” said Strelkov. “What we don’t know is if this was a naturally occurring strain that may have existed or whether it was in fact an erosion of the resistance.” Strelkov said researchers have just finished their greenhouse experiments and are conducting a second phase of experiments to learn more conclusively if what they’ve found is a new strain of clubroot or resistance erosion. “Right now, in this case, I can’t conclude one way or the other. I don’t think we have enough data to make such a conclusion. Right now I will call it a couple fields of concern.” Clubroot was first detected in a canola field in 2003 and has slowly spread to other parts of the Prairies.
The soil-borne disease creates galls, or clubs, on the roots of canola plants, which dramatically decrease yields. Researchers were quick to come up with new clubroot resistant varieties to allow farmers to grow canola in the clubroot hot spots. Many municipalities and counties had implemented bylaws allowing canola to be grown on infected land only every five to seven years in an effort to reduce the clubroot spores in the soil. However, the new resistant varieties allowed farmers to once again grow the valuable crop on infected fields. Strelkov said it wouldn’t be a surprise if resistance has started to break
down. Clubroot resistance was relatively short lived in parts of the United States and Europe after growers grew resistant varieties year after year, he added. Resistance breaks down when the same varieties are grown continually on the same field and new pathogens start to attack the resistant genotypes within the canola plant. “Resistance is such an important management tool. It is our main management tool,” Strelkov said. “It would be a shame if we started to lose resistance options because people are not rotating properly, particularly if they know they have heavy clubroot. It would be a shame.” SEE CLUBROOT IN CANOLA, PAGE 2
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