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Oral: Pathogen Dispersal


Timing of primary inoculum release by Monilinia vaccinii-corymbosi infecting blueberries in the US Pacific Northwest.
D. HARTEVELD (1), T. Peever (2), J. Pscheidt (3) (1) Washington State University, U.S.A.; (2) Washington State University, U.S.A.; (3) Oregon State University, U.S.A.

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Mummy berry, caused by Monilinia vaccinii-corymbosi, infects highbush blueberry (Vaccinium corymbosum) and causes severe economic losses in the Pacific Northwest (PNW). Control is mainly based on calendar-based fungicide sprays. The primary inoculum source is ascospores produced from apothecia that develop on mummified berries, or pseudosclerotia, that overwinter on the soil surface. Timing of apothecial development and ascospore release varies among locations and seasons, and differences in environmental factors may be why control programs are not always effective. This study aimed to identify environmental factors involved in the timing of primary inoculum release in the PNW, and develop a predictive model for ascospore release. Apothecial development was monitored in a severely affected field from 2008-2013 in Corvallis, Oregon and in two fields in northwestern Washington during the 2015 season. Data for eleven environmental factors was obtained from in-field weather stations and Washington State University’s AgWeatherNet. Soil temperature, solar radiation and precipitation were the most significant factors influencing apothecial development demonstrated by a generalized linear model regression analysis. A forecasting model developed to predict primary inoculum release is being validated for PNW locations during the 2016 season. Outcomes of this research will improve the timing of disease management practices and overall control of mummy berry in the PNW.