Novel UV-technology as a tool for management of diseases and pests in protected crops

Abstract: There is an increasing interest for technologies employing ultra-violet (UV) light as
a tool in integrated disease and pest management, and autonomous robots designed for UV-treatment of different crop types are now becoming commercialized. Brief UV (< 300 nm, 80-
200 J/m2 ) treatments efficiently controls powdery mildews on e. g., strawberry, grapes,
cucumber, tomato, ornamentals and various herbs. Under practical conditions, 2-3 weekly
treatments are sufficient to reduce the disease severity to an extent similar to or better than the best fungicides. Treatments must take place during night, because UV-A and blue light
appearing during daytime will repair some of the damage lower frequencies of UV does to the
fungus. UV-doses that efficiently control powdery mildew and are tolerated by plants has been found to reduce survival and offspring production of Tetranychus urticae and Myzus persicae if they are sufficiently exposed. However, how such UV-treatments will affect biocontrol agents are yet largely unknown. Trials in high plastic tunnels with strawberry indicated that UV-treatment by a robotic unit designed for powdery mildew control can be combined with use of the predatory mite Neoseiulus cucumeris. However, a growth chamber experiment indicated that UV may reduce performance of Aphidius colemani on sweet pepper infested with M. persicae.