Studies on fungicide treatment of soil and seed tuber for control of potato black scurf (Rhizoctonia solani Khun) in Argentina

Abstract: During 2008 to 2010 growing seasons, three trials were conducted on fungicide treatment of soil and seed tuber for control of potato black scurf at INTA Balcarce Experimental Station, Argentina in randomized complete block design. Before planting, fungicides Monceren 25SC (pencycuron 25%) at 1.25 L/t and Celest 25FS (fludioxinil 2.5%) at 0.5 L/t were sprayed on potato whole seeds. After planting, the same fungicides were sprayed on each row at 2.5 and 1.0 L ha^-1, respectively. Whole healthy (no symptons) and diseased (15-20% surface covered by sclerotia) seeds of Kennebec cultivar were used. Artificial inoculations to the soil were made with Rhizoctonia solani AG3 anastomosys group. Disease incidence was registered every year. Yields were recorded and each tuber was goruped according to health. Fungicides showed better results than both checks and reduced plant disease incidence in the field. Inoculated check showed 50% of unhealthy plants while the fungicides reduced it to 10%. Yield increase of marketable tubers was 42% better in fungicide treatments than in the inoculated check. Both fungicides produced more healthy tubers than the inoculated check or uninoculated check. Yield increase of healthy tubers was 45% higher when compared with the inoculated check. Fungicide seed treatment was better when disease seeds were used and fungicide soil treatment was better than healthy seeds.