Control of silver scurf on potato by dusting or spraying seed tubers with fungicides before planting

Silver scurf of potato caused by Helminthosporium solani Dur. & Mont. is a blemish disease that has become economically important in recent years and is considered primarily seedborne. The objective of the present study was to compare the effectiveness of various fungicides, alone or in combination, applied to seed tubers prior to planting, in controlling silver scurf on the daughter tubers. Disease incidence and severity were significantly reduced by all treatments in three experimental locations, with the exception of fluazinam, which was not effective. Among the fungicides tested in these experiments, the most effective were fludioxonil and prochloraz-Zn applied as a LV spray (control efficiency of 88% and 82%, respectively) and propineb and mancidan applied as a dust treatment (control efficiency of 78% and 77%, respectively). Azoxystrobin and imazalil treatments were less effective with control efficiencies of 68% and 43%, respectively. None of the various treatments affected crop yields in the three experimental sites.