Optimaztion of isolation and distribution of anastomosis groups of Rhizoctonia solani and determination of sources of inoculums in ornamental plants in Shiraz

Rhizoctonia solan AG-2 and AG-4 are main pathogens in ornamental plants in Shiraz but their sources of inoculum is not known. During 2013 and 2014 soil samples from different parts of Shiraz landscape, nurseries, sources of animal fertilizers, compost, vermin compost ,soil mix and Shiraz vicinities from cultivated and virgin soils were collected and assayed using sugar beet seeds as bait and plated on PDA supplemented with 100ppm PCNB and Chloramphenicole and 50ppm Hymexazole. 218 isolates of Rhizoctonia were recovered of which 193 multinucleate and 25 binucleate.Anastomosis groups of 50 multinucleate isolates were determined using 18 AG testers and the following AGs with their frequencies were found: Tweleve AGs included AG-4(36%), AG-2 (18%), AG-1-1A (18%), AG-2-IIIB(6%), AG-3, AG-2-2 and AG-13 ( 4%), AG-2-C, AG=5, AG-7 and AG-11(2%) in field soil and AG-BI (2%) in virgin soil. No Rhizoctoniawere recovered from in front of soil mix, animal fertilizers and composts used for potting and nurseries..It was concluded that transplants from nurseries are the main sources of inoculums.