The effect of inoculum distribution and sowing depth on Pleiochaeta root rot of lupins

Abstract

In paddocks with a history of previous lupin cultivation, propagules of the fungus Pleiochaeta setosa are most concentrated in the top 2 cm of soil and rapidly decline to zero at the base of the tillage layer (10-14 cm). The severity of Pleiochaeta root rot is greatly reduced as sowing depth increases, due to avoidance of the concentrated surface soil borne inoculum. Hypocotyls are not infected by P. setosa, enabling disease escape. In four field trials over three seasons, optimum establishment and grain yield occurred at sowing depths close to 5 cm, deeper than previously recommended for lupins in Western Australia.