Inactivation of plant infecting fungal and viral pathogens to achieve biological containment in drainage water using UV treatment

Aim: To explore whether ultraviolet (UV) light treatment within a closed circulating and filtered water drainage system can kill plant pathogenic species. Methods and Results: Ultraviolet experiments at 254 nm were conducted to determine the inactivation coefficients for seven plant pathogenic species. At 200 mJ cm^?2, the individual species log reductions obtained for six Ascomycete fungi and a cereal virus were as follows: Leptosphaeria maculans (9·9‐log), Leptosphaeria biglobosa (7·1‐log), Barley stripe mosaic virus (BSMV) (4·1‐log), Mycosphaerella graminicola (2·9‐log), Fusarium culmorum (1·2‐log), Fusarium graminearum (0·6‐log) and Magnaporthe oryzae (0·3‐log). Dilution experiments showed that BSMV was rendered noninfectious when diluted to >1/512. Follow‐up large‐scale experiments using up to 400 l of microbiologically contaminated waste water revealed that the filtration of drainage water followed by UV treatment could successfully be used to inactivate several plant pathogens. Conclusions: By combining sedimentation, filtration and UV irradiation within a closed system, plant pathogens can be successfully removed from collected drainage water. Significance and Impact of the Study: Ultraviolet irradiation is a relatively low cost, energy efficient and labour nonintensive method to decontaminate water arising from a suite of higher biological containment level laboratories and plant growth rooms where genetically modified and/or quarantine fungal and viral plant pathogenic organisms are being used for research purposes.