Anastomosis Groups and Pathogenicity of Rhizoctonia solani Kühn Isolates Isolated from Pistachio (Pistacia vera L.) Saplings in Siirt Province, Turkey

Pathogenicity and anastomosis groups of seven Rhizoctonia-like isolates obtained from infected pistachio (Pistacia vera L.) seedlings were determined, in the central district of Siirt province at Southeast Anatolia Region in Turkey. Browning on the crown root of the collected saplings and drying of plants were observed. In the pathogenicity test, the most virulent isolate was Rs2 with a disease severity of 93.75%. The anastomosis group of this isolate, which caused the saplings to dry completely was determined as Rhizoctonia solani AG-4. The moderately virulent Rs3 and Rs1 isolates were determined as the binucleate AG-F group. These two isolates caused yellowing of the seedling leaves and browning of the roots, however, the plants did not die and preserved their vitality to a certain extent. The R9 and R14 isolates identified as anastomosis group AG-F did not cause any symptoms on inoculated plants and on the negative control. The Rs7 and Rs10 isolates were identified as the anastomosis group AG-4 and were determined to be pathogenic in saplings. The results of this study are the first record for the virulence and anastomosis groups of Rhizoctonia species that cause root and crown root diseases in Siirt pistachio.