Assessing the Efficacy of UV-C Light for the Inactivation of Phytopythium and Phytophthora Species in Water: A Mathematical Modeling Approach Using an Ultraviolet Light-Emitting-Diode System

Abstract

The use of untreated, recirculated irrigation water is a profitable practice, but it can harbor plant pathogens such as Phytophthora ( Pt) cinnamomi, Pt. nicotianae, Phytopythium ( Pp) vexans, and Pp. helicoides, posing disease risks in crop production. UV-C (240 to 290 nm) light-emitting diode (LED) irradiation was evaluated for inactivating the zoospores of oomycetes in water, providing potential for effective treatment. Zoospore suspensions were exposed to quantifiable UV-C doses under dynamic stirring, calculated by multiplying fluence rate (mW cm−2) and exposure time(s). UV-C irradiation effectively inactivated the tested pathogens following linear (logarithmic linear [ Pt. cinnamomi and Pt. nicotianae]) and nonlinear (Weibull and Weibull + tail [ Pp. vexans and Pp. helicoides]) kinetics as identified by parameters of goodness of model fit: high R2 and low root mean square error (RMSE) values. D10 values of Pt. cinnamomi and Pt. nicotianae calculated from the rate constants ( Kmax) of the log-linear models were 5.05 ± 0.38 mJ cm−2 ( R2 = 0.95, RMSE = 0.091, Kmax = 0.49 ± 0.03) and 4.73 ± 0.33 mJ cm−2 ( R2 = 0.96, RMSE = 0.091, Kmax = 0.49 ± 0.03), respectively. The Weibull + tail model best described the inactivation of Pp. vexans ( R2 = 0.97, RMSE = 0.099) and Pp. helicoides ( R2 = 0.96, RMSE = 0.083), and the δ and Nres values were determined to be 9.88 ± 0.12 and 2.06 ± 0.06 and 11.47 ± 0.38 and 2.45 ± 0.05, respectively. These study findings can be applied to develop water disinfection systems, either alone or in combination with other methods, for effective control of pathogens in irrigation systems. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .