Affected Patches Appearing – Find out Why

At this time of year (as the canola crop finishes flowering and begins to pod), stressed or affected patches often appear within the field. These patches are usually most noticeable because they started flowering at the same time as the rest of the field but are now coming out of flower sooner. If possible, mark these suspicious patches so they can be examined more closely to determine what is happening with the canola crop. Are these stressed patches located on knolls (e.g. lacking moisture sooner or could soil fertility be playing a role)? Are root maggots present? Pull plants with roots intact and check for root maggots. Plant disease symptoms can also begin to appear at this time so take a closer look to determine if blackleg or sclerotinia stem rot are present.  Clubroot disease may be another potential explanation. In the first few Canola Watch issues this spring, it was reported that a soil test from west-central Saskatchewan had shown the potential presence of the clubroot pathogen’s DNA. Further testing was being conducted to confirm the results. SaskCanola recently reported that the DNA diagnostic test and a canola plant bioassay confirmed that trace levels of the clubroot pathogen (Plasmodiophora brassicae) were present in that soil sample. More information is found in the press release issued at: http://www.saskcanola.com/news/2009-0721-clubroot.html

While scouting, it is important to follow field entry protocols to maintain proper sanitation and limit the spread of clubroot. More information on sanitation guidelines is available at the following link:  http://www.canolacouncil.org/clubroot/docs/field_entry_1.pdf and more general information on clubroot is available at http://www.clubroot.ca/