Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2015
Publication Date: 3/15/2015
Citation: Janisiewicz, W.J., Takeda, F., Smith, B.J., Glenn, D.M. 2015. Alternative strawberry disease management strategy: combing low UV-C irradiation in dark, disabling pathogen’s UV-C repair mechanism, and preventing pathogen establishment with biocontrol agents [abstract]. North American Strawberry Growers Association. p. 20.
Technical Abstract: The limitations of current fungicides necessitate a search for new approaches. Low-dose or sub-lethal UV-C irradiation (12.36 J/m2) alone is not effective in controlling fungal diseases, especially when the plants are exposed to UV-C irradiation during the day. We found, however, that application of UV-C irradiation at night, even at previously considered sub-lethal levels, was highly effective in killing Botrytis cinerea, Colletotrichum acutatum, and Podosphaera aphanis. A four-hour dark period after the UV-C exposure prevented these fungi from initiating the chain of events for activating the cellular mechanism to repair the damage caused to the DNA by UV-C radiation. As a result, a complete kill of B. cinerea conidia on agar media and P. aphanis on the leaves was achieved. Conidia of C. acutatum were even more susceptible under these conditions. The UV-C dose used for microbial control did not affect photosynthetic capacity of strawberry leaves or discolor sepals, even after repeated exposure for seven weeks. Irradiation of strawberry pollen did not affect pollen germination, tube growth and length in vitro, or germination and tube growth in the style of hand pollinated emasculated strawberry flowers. This UV-C treatment may be useful for controlling gray mold and other diseases in tunnel and intensive field production of fruits and vegetables, providing that a four-hour dark period follows the UV-C treatment. Microbial antagonists applied immediately after the UV-C treatment fill the microbiological “vacuum” created by the night-time UV-C exposure to prevent re-colonization of strawberry plants by fungal pathogens.