Effect of Fungicide Treatment on Silver Scurf Management and Potato Yield

Silver scurf, caused by the fungus Helminthosporium solani, has become a growing potato disease concern in the United States. Conventional cultural management practices are often impractical or insufficient at a commercial scale, underscoring the need for effective fungicide treatments in integrated management approaches. H. solani initially infects tubers in the field, and secondary infection cycles could occur during storage. Inoculum could possibly be reduced at multiple stages during production. This study, conducted from 2015 to 2018, evaluated the effects of various fungicide treatments on silver scurf severity, potato emergence rate, and marketable yield. Fungicides were applied at three stages: (i) at planting, either as seed treatment or an in-furrow application; (ii) during field production as foliar treatment; and (iii) postharvest, prior to storage. We found seed treatment, either alone or in combination with foliar application, significantly reduced silver scurf severity at harvest in 3 of the 4 years of study. Additionally, seed treatment alone significantly reduced tuber disease severity after 90 days of storage in 2 of the 4 years. Postharvest treatment with Stadium, applied prior to storage, effectively reduced silver scurf severity after 90 days of storage in 2 of the 4 years of the study. Our fungicide evaluation results provide updated insights for growers seeking to optimize fungicide use for silver scurf management.