Exploring Ultraviolet C Irradiation as a Control for Oomycete Pathogens of Stored Potato
Storage diseases of potato are notoriously difficult to control and can cause substantial loss of raw product. Control methods for most storage diseases are limited to a few fungicides applied directly to the tubers post-harvest. For nearly a century the germicidal effect of Ultraviolet C (UVC) irradiation has been well known. The advent of new UVC-emitting technologies, along with a reduction in cost, has led to the adoption of UVC as a sanitizing step in many food production industries. UVC has not yet been implemented in potato production. An initial screen of potato pathogens for susceptibility to UVC irradiation in vitro showed a trend of non-pigmented pathogens exhibiting greater sensitivity to the irradiation. Oomycete pathogens, in particular, were most sensitive. Storage trials were conducted with Russet Burbank, Dark Red Norland, and Snowden varieties to evaluate UVC irradiation in limiting disease on tubers post inoculation. Tubers inoculated with Phytophthora erythroseptica, and then irradiated with UVC resulted in a nearly 50% decrease in disease incidence compared to the untreated control. Trials are underway to evaluate efficacy against the oomycetes P. infestans and Pythium ultimum. Trials were also conducted to evaluate the impact of UVC irradiation on tuber physiology. Metrics including sugar content, fry color, greening, and germination rate were evaluated with no apparent differences between UVC irradiated and non-treated controls.