Rotation’s role in clubroot management

At CanoLAB Saskatoon, Gary Peng from AAFC showed these photos from clubroot trials in Quebec. Clubroot resistant (R), moderately susceptible (MS) and susceptible (S) canola varieties were grown on clubroot infested soil on rotations that ranged from continuous canola to canola every 5 years. The photos show how rotation, especially for MS and S varieties, improves yield. Rotation also plays an important role for growers relying on R varieties in clubroot infested fields. Short rotations using resistant varieties will select quickly for clubroot pathotypes that are not controlled by the genetic resistance. This can rapidly eliminate the value of the resistance trait on those fields, which is a situation that has already been experienced in canola and cole crops around the world.