Identification of Potato Rhizoctonia Anastomosis Groups in Hamadan and Kurdistan Provinces and Survey of Their Biological Control Possibility using Trichoderma spp.

During survey of potato Rhizoctonia disease in 2006، 50 isolates with characters of Rhizoctonia solani fungus from stems and roots and eight isolates from sclerotia، on potatoes surface، were obtained from fields and storages of Hamadan and Kurdistan Provinces. After nuclear staining and physiological surveys، all of the isolates identified as R. solani. For determining anastomosis groups of isolates، anastomosis carried out with tester isolates. Finally، 56 isolates belonged to AG-3، one isolate belonged to AG-4 and one isolate did not anastomoses with any available tester anastomosis groups in this study. Pathogenicity test of 25 isolates shown they are virulence. Biocontrol potential of four species of Trichoderma، including T. brevicompactum، T. koningiopsis، T. andinensis، and T. virens were studied on two pathogen isolates (6 and 16)، that had highest pathogenicity in pathogenicity test، in laboratory. Results showed that except T. andinensis، other Trichoderma spp. developed، establish and sporulated on pathogen colony after stopping its growth and destroyed pathogen hypha as coiling them. Volatile compounds of all Trichoderma spp. had significant effects on reducing pathogen isolates growth and among them T. virens، T. koningiopsis and T. brevicompactum had a higher inhibition، respectively.