Evaluation of the effect of potato seed disinfection with chemical compounds in control of rhizoctonia canker and black scurf of potato

Potato black scurf and rhizoctonia canker caused by Rhizoctonia solani is one of the most common diseases in all potato growing areas of Iran. Due to the importance of seed disinfection in the control of this disease, in this study, the effect of seed disinfection with fungicides Iprodione carbendazim WP52.5%, Thiabendazole WP60%, Thiophanate methyl WP70%, Carboxin thiram FL40%, Carboxin thiram WP75%, PencycuronWP25%, Fludioxonil FS2.5%, Mancozeb WP80% and Carbendazim WP50-60% in the laboratory and greenhouse was investigated. Iprodione carbendazim with concentration of 2.5/1000 with 71.5% had the highest of percentage inhibition on germination of sclerotia and with a concentration of 20 ppm and 77.5%, inhibited the growth of fungal mycelium on potato dextrose agar (PDA) medium. In greenhouse, the plants from seed treatment with Iprodione carbendazim, Thiabendazole and Carboxin thiram FL40% each with a concentration of 2.5/1000 had the highest daughter tubers production with about 260-270 g. This treatments without any canker on underground stem and zero percent of infected plant were the most effective treatments and there was no significant difference between them. In the study of the number of sclerotia on the surface of the tuber, Iprodione carbendazim, Thiabendazole and Carboxin thiramWP75% each with a concentration of 2.5/1000 with an average of three sclerotia had the greatest effect on reducing the number of sclerotia on the daughter tubers. In general, according to the results, all studied fungicides had a positive effect on disease control and yield increase but Iprodione carbendazim with a concentration of 2.5/1000 was the most effective fungicide for controlling potato rhizoctonia canker.