Wild Blueberry Newsletter, Early March 2025
Wild Blueberry Newsletter
Early March 2025
Phenology Report
Jordan Parks visited our four overwintering weather stations and reports back that as of February 26th sites from Warren to Whiting were covered in snow. Snow cover insulates this year’s buds protecting them from harsh winter winds.
NOAA Climate Outlook
The April, May and June weather outlook provided by NOAA can be found here. They predict temperatures to be leaning higher than normal and precipitation to have equal chances of being high or low.
Powdery Mildew Notice
By Dr. Seanna Annis
There are reports in the news of a “new” powdery mildew fungus (Erysiphe vaccinii) that is attacking blueberries around the world. The major interest in this fungus is because it has spread to countries that have recently started planting cultivated blueberries, such as China, Morocco, Peru, and Mexico, and the disease is causing an increase in their production costs due to the use of fungicides to control this disease. This “new” powdery mildew probably originated from the Northeast since it is very similar to types found in our fields and Massachusetts. The fungus spread from North America to new locations probably through infected plants. The same fungus occurs in North Carolina’s blueberry breeding facility that occurs in other countries.
Powdery mildew has been a minor pathogen in wild blueberries in Maine. Powdery mildews can weaken plants, but not kill them, and decrease yields by using sugars the plant produces that the plant could be using to make fruit. This fungus is found in almost all fields in Maine but seems to cause very little damage to the plant. Wild blueberry fields have more tolerance to infection by powdery mildew than most rabbiteye and highbush blueberry varieties. Most cultivated blueberries are breed for yield characteristics and rarely for disease resistance and are typically planted with only one or few varieties in a field. If a cultivated blueberry variety is susceptible to the fungus, it can spread rapidly and affect many plants or all of the plants in a field. Wild blueberries are resistant to powdery mildew damage because of their high genetic diversity and therefore they have a large diversity in susceptibility and resistance, so while one clone may be badly infected most around it will have a different level of resistance. Another factor is that powdery mildew evolved with blueberries in the Northeast and so our lowbush blueberries have evolved more resistance to this disease. Questions? Reach out to Seanna at sannis@maine.edu.
Your input needed on Spotted Wing Drosophila!
As part of a national team of entomologists studying the management of spotted-wing drosophila (SWD), we are reaching out with a request for assistance to help understand the current impacts of SWD on your farm and how these impacts may have changed in the last 10 years.
If you are willing to share insights from your farm, farms you manage, or growers you work with, please complete this short survey, which will take about 15 minutes or less: complete the survey here.
How will this information be used? This information will be used to develop new research goals as part of a USDA Specialty Crop Research Initiative proposal under development. It will also be compared to information collected in similar surveys in 2013 and 2014 to help us understand where challenges still exist for SWD management.
Upcoming Events
New Brunswick Maritime Blueberry Conference
Date: April 11&12, 2025
Location: Delta Holel, 750 rue Main Street, Moncton, New Brunswick
Contact: Noelle LeBrun at n.lebrun@bellaliant.net with questions
Registration Form
Maine Spring Wild Blueberry Field Days
May Sprayer Calibration and IPM Field Day Dates Coming Soon
Maine Blueberry Hill Farm Field Day
Date: June 26, 2025
Location: Blueberry Hill Farm, 1643 US Rt-1, Jonesboro, ME
Nova Scotia Wild Blueberry Feld Day
Date: July 16, 2025
Location: Truro, NS area TBD
Quebec Wild Blueberry Field Day
Date: Week of July 14th TBD
Location: Normandin, QC area TBD
All the best,
Lily
Dr. Lily Calderwood
Extension Wild Blueberry Specialist
Associate Professor of Horticulture
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