Discipline: Biological Sciences
Gina Dabbah - California State University, Monterey Bay
Co-Author(s): Timothy Miles, School of Natural Sciences, California State University Monterey Bay, Seaside, CA Annemiek Schilder, Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI
Monilinia vaccinii-corymbosi (Mvc) is the causal agent of a disease known as mummy berry in highbush blueberries (Vaccinium corymbosum L.). The primary inoculum of Mvc consists of ascospores that are discharged from apothecia on overwintered mummified blueberry fruits on the ground below blueberry bushes. Models currently exist in southern climates to predict the emergence of apothecia and ascospore discharge based on chill hours and growing degree days. In order to better understand the release of primary inoculum in northern climates, we studied apothecial emergence and ascospore discharge in relation to weather variables. The chilling requirement of pseudosclerotia was studied by removing them at different times during the winter months and allowing them to germinate in the laboratory. A Burkard spore trap was used to collect ascospores within blueberry fields with a history of the disease in 2002, 2003, 2004, and 2009. Hourly peak ascospore within a single day discharge was inversely correlated with hourly relative humidity, and the majority of ascospores were discharged seasonally after 3000 chill-hours (<7.2°C) were attained and 650 and 1300 growing degree-days (base 7.2°C) starting from September 15th of the previous year. Additionally, the relationship of average apothecial cup diameter to ascospore discharge was investigated. Maximum ascospore discharge occurred when apothecia were between 2 to 7 mm in diameter. Finally we propose a simplified degree-day model to predict apothecium emergence and ascospore discharge. This model was validated by observations of apothecium emergence field locations from 2007-2010. The information in this study may be used to predict mummy berry inoculum availability and be incorporated into web-based risk modeling applications with the aim of providing growers with useful tools to improve fungicide spray timing.
Funder Acknowledgement(s): We thank the following for funding: -Undergraduate Research Opportunities Center (UROC) at CSUMB -The Blueberry People -Project Greeen (Generating Research and Extension to meet Economic and Environmental Needs). We thank the following for assistance: -April Sanders -Roger Sysak -growers for use of their field sites.
Faculty Advisor: Timothy Miles, firstname.lastname@example.org
Role: I compiled and formatted these data, ran all statistical analysis, and created the graphs, tables, and poster. I created the degree day model to ultimately upload to an easily usable online platform for farmers to spray targeted fungicides in order to combat the disease. I am also writing the manuscript in conjunction with my adviser.