Inactivation of Cercospora lactucae-sativa through Application of Non-Thermal Atmospheric Pressure Gliding Arc, Tesla Coil and Dielectric Barrier Discharge Plasmas

Cercospora leaf spot disease is a serious problem for lettuce cultivation worldwide. Cercospora lactucae-sativa, the causative agent of leaf spot disease on lettuce, was treated with non-thermal atmospheric pressure gliding arc (GA), tesla coil (TC) and dielectric barrier discharge (DBD) plasmas for the in vitro fungal inactivation of both mycelial growth and conidial germination. The fungus was exposed to the three plasmas individually for 5, 10, 15 and 20 min. The results showed that DBD plasma inactivated fungal growth during all exposure periods, and the highest inhibitory effect was caused by exposure to DBD plasma for 20 min, at 93.33% inhibition. The germination of fungal conidia was completely inactivated after exposure to all three non-thermal plasmas for 5 min, as observed 4 and 24 h after incubation. The pathogenesis of C. lactucae-sativa on lettuce after plasma treatments for 5 min was examined by spraying an inoculation of the treated conidia on lettuce. The results showed that all three plasmas reduced the disease incidence and severity compared to the non-treated control. Therefore, the non-thermal atmospheric pressure GA, TC and DBD plasmas have antifungal potential for the inactivation of C. lactucae-sativa, making them an interesting novel technology for plant disease control.