Control of Fungal Spores on Surfaces with UV-C Exposure Necessitates Complete Inactivation to Prevent Mycorrhizal Network Establishment

from 265 nm LEDs achieved complete preinactivation at lower concentrations (100-1000 CFU/plate), while higher concentrations required increased UV-C doses. Intermittent duty cycling of light delivery (10 min ON then 50 min OFF) at 275 nm delivered from side-emitting optical fibers achieved comparable mitigation to continuous irradiation. Insufficient UV-C exposure induced more resistant mycelial structures that shielded live spores beneath. This study highlights complete preinactivation of viable molds, or sustained inhibition by UV-C light, is more effective than UV-C posttreatment. Mycelial alteration triggered by sublethal stress helps spores to persist in unfavorable environments, where microbial control is the goal.