To:

• test whether addition of carbon to soil as stubbles or roots suppressed rhizoctonia severity in a following cereal,
• investigate whether the effect of stubbles carbon was similar or different to root carbon, and
• measure the presence of specific suppressive microbes.

• Recent carbon inputs positively influence the ability of a soil to suppress Rhizoctonia.
• Adding carbon as stubble or roots to Eyre Peninsula soils reduced infection of wheat seedling roots by Rhizoctonia solani AG-8.
• DNA of potentially suppressive microbes tended to increase in the soil after stubble or root addition and the effect was often greater from roots.