Root pathogens detected in irrigation water of the Ord River Irrigation Area

Expansion of the Ord River Irrigation Area in Kununurra, Western Australia is currently in progress, and subject to various environmental controls, including the implementation of irrigation tailwater management (recycling) systems. The aim of this research was to determine the presence of plant pathogens in the irrigation water in the irrigation area; and to ascertain what impact they could have if tailwater is recycled. Surveys were conducted during the 2010 and 2011 dry seasons to determine the presence of Phytophthora and Pythium species in the irrigation water and the pathogenicity of isolated species was assessed against two commercial crops – butternut pumpkin and chia. Several pathogenic isolates caused damping-off or distorted primary and lateral root growth. These preliminary findings demonstrate the presence of plant pathogens in the irrigation water, and the need for further investigation to assist with their management in the tailwater.