UV‐C irradiation as a management tool for Tetranychus urticae on strawberries.

BACKGROUND: Tetranychus urticae Koch, the two‐spotted spider mite, is a highly polyphagous and worldwide pest of many agricultural crops, including fruit, vegetables, and ornamentals. Typical methods of control include applications of acaricides and biological control agents. Here, we present a non‐chemical technology for management of T. urticae on strawberry plants through the use of a nightly short‐duration ultraviolet‐C (UV‐C) irradiation treatment. RESULTS: Potted strawberry plants infested with T. urticae that received a nightly 60‐s exposure of UV‐C irradiation had significantly fewer live mites per mid‐canopy leaflet (fewer than five) than untreated control plants (> 175). Furthermore, none of the UV‐C irradiated strawberry plants had any spider mite webbing; whereas, 65% of untreated plants were webbed. Tetranychus urticae feeding on untreated plants caused significant yellowing of the leaves compared with UV‐C‐treated plants. CONCLUSION: The UV‐C irradiation treatment maintained mite populations below the accepted economic threshold of five mites per mid‐canopy leaflet. No phytotoxic effects were visible on plants exposed to the short‐duration nightly UV‐C irradiation treatments. Further discussion is provided on the potential benefits of UV‐C irradiation for mite management. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. Tetranychus urticae is a severe pest of strawberry plants worldwide. Nightly, short‐duration treatments of ultraviolet‐C irradiation provides an effective non‐chemical management strategy for T. urticae. [ABSTRACT FROM AUTHOR]