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New technology for controlling strawberry diseases and arthropods

Wojciech Janisiewicz: USDA-ARS AFRS

<div>Fungicides are the main weapon for controlling diseases of strawberries; however, their use has various problems including development of resistance in pathogens, restrictions on their use especially in protective culture, and a growing public demand for produce free of pesticide residues. Our research has been focused on developing alternative strategies that address those limitations. We developed PhylloLux<sup>©</sup> technology which encompasses night-time UV-C irradiation for 60 sec (12.3 J/m<sup>2</sup>) twice a week followed by application of antagonists <em>Aureobasidium pullulans</em> and <em>Metschnikowia pulcherrima</em>. We identified that specific dark periods (2-4 h depending on pathogen) immediately following UV-C treatment prevented activation of a light-induced fungal DNA repair mechanism increasing the killing power of the UV-C treatment 6 to 10-fold and making this approach practical because effective irradiation doses were not toxic to plants and the energy cost was substantially reduced. The treatment was effective against gray mold (<em>Botrytis cinerea</em>), powdery mildew (<em>Podosphaera aphanis</em>) and anthracnose (<em>Colletotrichum</em> spp.). The two antagonists filled the microbial void after UV-C treatment, prevented recolonization by unwanted microbes and increased robustness of the control. In recent studies, nightly irradiation alone vastly reduced infestation by two-spotted spider mites (<em>Tetranychus urticae</em>). The PhylloLux<sup>©</sup> technology also may be applicable in vegetable and ornamental production.</div>