Non-chemical control of powdery mildew in strawberry

Authors: STENSVAND, ARNE - Norwegian Institute Of Bioeconomy Research(NIBIO); SUTHAPARAN, ARUPPILLAI - Norwegian University Of Life Sciences; ASALF, BELACHEW - Norwegian Institute Of Bioeconomy Research(NIBIO); ONOFRE, RODRIGO - University Of Florida; PERES, NATALIA - University Of Florida; Turechek, William; BIERMAN, ANDREW - Rensselaer Polytechnic Institute; REA, MARK - Rensselaer Polytechnic Institute; GADOURY, DAVID - Cornell University

Submitted to: IOBC/WPRS Bulletin (Abstract for Conference Proceedings)
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2018
Publication Date: 9/5/2018
Citation: Stensvand, A., Suthaparan, A., Asalf, B., Onofre, R., Peres, N., Turechek, W., Bierman, A., Rea, M., Gadoury, D. 2018. Non-chemical control of powdery mildew in strawberry. IOBC/WPRS Bulletin (Abstract for Conference Proceedings). 978-9934-19-641-6.

Interpretive Summary: Widespread fungicide resistance among strawberry pathogens, as well as public pressure to reduce chemical use, has spurred a search for alternatives to chemical control. High tunnel production systems have reduced losses from gray mold, but elevated severity of powdery mildew. We explored and refined several non-chemical means to control strawberry powdery mildew. First, mobile robotic and tractor-drawn units with ultraviolet (UV) lamp arrays were designed and deployed, and suppressed powdery mildew in greenhouse, high tunnel and field production by more than 90 %. The use of UV-transmitting plastics in field-based, low tunnels reduced powdery mildew to levels approximating that observed in open field plantings. Third, carefully timed brief overhead sprinkling with water further reduced powdery mildew nearly as efficiently as the best fungicide treatments. Lastly, precisely regulated steam in a 2-stage process has been used to reduce or eradicate several strawberry pathogens.

Technical Abstract: Widespread fungicide resistance among strawberry pathogens, as well as public pressure to reduce chemical use, has spurred a search for alternatives to chemical control. High tunnel production systems have reduced losses from gray mould (Botrytis spp.), but elevated severity of powdery mildew (Podosphaera aphanis). We explored and refined several non-chemical means to control strawberry powdery mildew. Mobile robotic and tractor-drawn units with ultraviolet (UV) lamp arrays were designed and deployed, and suppressed powdery mildew in greenhouse, high tunnel and field production by more than 90 %; a level of efficacy comparable to the best available fungicides. Conventional glass, polyethylene, and polycarbonate plastics block nearly all solar UV-B. When UV-transmitting fluorocarbon plastics were used in tunnel construction, powdery mildew was reduced to levels approximating that observed in open field plantings, largely eliminating the stimulation of disease that had been widely attributed to elevated RH and temperature in such structures. Carefully timed brief overhead sprinkling with water has further reduced powdery mildew nearly as efficiently as the best fungicide treatments. Meteoric water droplets have removed Podosphaera aphanis conidia and physically damaged mildew colonies. Lastly, we have used precisely regulated steam in a 2-stage process to pre-treat transplants to simulate host tolerance of heat, followed by a warmer therapeutic temperature to eradicate pathogens.