31 Advancing Seed in Alberta | spring.2018 “We continue to have good resistance genes available, and what’s changed is that we now need to actively manage the crop resistance genes we present to blackleg fungus populations,” he explains. “So, frequent and accurate scouting with excellent record keeping is essential for determining if the genes we’re presenting are working or not. Then, producers need to eliminate the non-functioning resistance genes when selecting which canola cultivar to plant (at least one functioning resistance gene).” This is now much easier, Lange notes, because seed companies are starting to reveal which genes are in which cultivar. Another tool for blackleg management is fungicides. Harding notes while all certified canola seed is cleaned and treated to make it essentially blackleg- free (although infection can still occur due to spores being released from infected stubble), in high-risk situations during the growing season, foliar fungicides may be applied at the one-to- three leaf stage. Going forward, Harding says the risk of resistance-building in the pathogen is very real when crop rotation “While we are not currently seeing widespread changes in blackleg severity, it has been seen in some individual fields. This is a warning sign that we need to think carefully about crop rotation practices and resistance stewardship in order to stay ahead of blackleg.” Clubroot In canola, this soil-borne fungus-like disease causes swellings to form on the roots, ultimately stunting the plant and even causing premature plant death. Infection and severity are supported by warm, moist, acidic soil. University of Alberta scientists and staff from Alberta Agriculture and Forestry currently conduct yearly clubroot surveys, which began in 2003 when clubroot was first identified in the province. The 2016 survey found 289 new clubroot-infested fields and the 2017 survey another 301. “What we've found is that clubroot is spreading fairly rapidly for a soil- borne plant pathogen, and this seems to be due mainly to the movement of infested soil and machinery,” explains Stephen Strelkov, professor in the faculty of Agricultural, Life and Environment When blackleg-infected seed is sown, the seedlings that emerge may be infected with lesions on the seedling leaves or stems. Photo courtesy Michael Harding, AAF recommendations are ignored, especially in wetter years when blackleg has a better chance to infect and cause disease. “If genetic resistance were to erode due to selection of virulent pathotypes of the fungus, it would have a devastating impact in areas where genetic resistance was no longer effective,” he notes.