Rhizoctonia root rot of beet

The primary causal agent of the disease is the fungus Rhizoctonia solani, which consists of a complex of genetically isolated anastomosis groups. Less frequently, the infection is associated with the species Rhizoctonia violacea. The pathogen attacks the root system, causing dry rot ranging from brown to black, which begins at the bottom of the root and spreads toward the crown, often accompanied by deep cracks and deformation of the taproot.

Above-ground symptoms typically appear after row closure. Spots develop on the leaves, leading to yellowing and wilting; the dry brown leaves do not fall off but remain on the crown, forming a characteristic "brown rosette." The disease most often develops in patches, and there are no specific resistance genes in standard nomenclature, meaning that varietal protection is based on quantitative traits.