Pathogenicity Test and Anastomosis Group of Rhizoctonia solani the Causal Organism of Stem Canker and Black Scurf Disease of Potato in Egypt

Stem canker and black scurf caused by Rhizoctonia solani Kuhn is considered the most destructive diseaseand reduce productivity of potato. Pathogenicity test of 12 isolates of R. solani obtained from two governorates, El-Sharkiya (New El–Salhia region) and Ismailia (El-Shabab region) revealed that all isolates were pathogenic, howeverisolate No.RS7 was the most virulent isolate in the development of the stem canker and black scurf disease. Moleculartechnique using PCR applied to determine anastomosis group of isolate No. RS7 showed that this isolate belong toAG3.