Output Reduction over Time of Germicidal UV-C Lamps Used for Treating Agricultural Crops

It is important in understanding the potential benefits of ultraviolet (UV-C) field applications for control of powdery mildew to know how long the lamps will last before replacement. We conducted a laboratory evaluation of a sample of low-pressure discharge germicidal UV-C lamps that have been used in field trials to control strawberry powdery mildew. None of the lamps tested failed to start after more than a year of operation. The degradation of UV-C output followed trends similar to those described by the manufacturer. Based on these measurement data and on the long history of this lamp technology, we predict that these lamps can continue to perform in the field after the manufacturer's rated life of approximately 10,000 hours of continuous operation, by reducing the speed of application to deliver the prescribed UV-C dose. With protective sleeves, these low pressure discharge UV-C lamps can be expected to last for many years of service.