Rhizoctonia root rot is a common soil-borne pathogen of many vegetable crops. Diagnostic features of Rhizoctonia include the brown 'shoe-string'-like hypha that are visible growing on the surface of the infected root with the naked eye or 10x hand lens.
Up close under a light microscope you can see the brown hypha that grow inbetween infected cells and on the surface of the infected root. Another feature of Rhizoctonia is that it always "branches" at 90 degree angles.
For more information please see the 2011 Commercial Vegetable Production Recommendations Guide.
- Andy Wyenandt