Hello, everyone
The last few days’ warm weather and moisture across mainland areas advanced crop development in wild blueberry fields, particularly in fruit bud F2 growth.
In some early regions (Table 1), crop fields have reached 40% F2 or above (some South Shore fields), which indicates that a Monilinia Blight fungicide spray may be needed when conditions are favourable. However, it is still early for a
fungicide program to be implemented in most central and northern fields. According
to forecasts, the weather is expected to further advance the F2 stage over the next few
days. A warm and moist field condition also helps mummy berry cup development
and disease spore infection.
Hopefully, this early-season blight line post will
give you firsthand information on monitoring your field crop stages and
preparing for this blight season’s management plan.
This season’s crop development and blight monitoring
are slower than last spring's. In spring 2024, we started the first blight line
post on April 11, but this year, it is on April 28 (about two weeks
later).
This post includes updates on:
-
Wild Blueberry Weather Station GDD and Crop
F2 stage updates
-
General information about Monilnia Blight
and Management
Wild Blueberry Weather Station GDD and Crop F2 stage updates
We selected the following 19 weather stations to report their seasonal Growing Degree Days (GDD) accumulations. Please compare the cumulative GDD from your weather station with local GDD recommendations on wild blueberry crop stages: https://www.novascotiawildblueberryblog.com/p/phenology-tracker.html.
Figure
1. Selected Wild Blueberry Weather Stations and GDD Updates (April 1- April 27)
Table
1. Wild Blueberry Weather Stations and GDD Updates (April 1- April 27)
The table below shows some available F2% information from
different regions.
Table 2. Percentage of Wild Blueberry Floral Bud F2
stage
light green (0-20% F2), dark green (20-30% F2), yellow
(30-40% F2) and red (40-100% F2)
|
Wild blueberry production regions, NS |
The average percentage of floral buds at
F2 |
|
|
|
|
Cape Breton |
|
|
|
|
|
Cumberland County |
|
|
|
|
|
South West Nova Scotia |
|
|
West Caledonia |
35-40% F2- April 28 |
|
|
|
|
Hants County |
|
|
|
|
|
Halifax County |
|
|
|
|
|
Guysborough County |
|
|
|
|
|
Colchester County |
|
|
Murray Siding |
30% F2- April 28 |
|
Camden |
25% F2- April 28 |
|
|
|
|
Pictou and Antigonish County |
|
|
|
|
General Information about Monilinia Blight and Management
Here are some recommendations
for managing Monilinia Blight.
1. If
fields have a past history of Monilinia Blight and the infection persists over
the years, it is important to watch for F2 development and local weather conditions
to prepare for fungicide applications.
2. Knowing
the F2 percentage of your fields is essential for timely application (Figure 2).
You can randomly walk your fields in a “W” pattern and collect 20-30 stems.
From those collected stems, count the total number of floral buds and the
number of buds at the F2 stage or beyond. Use the following formula to get a
single stem F2%:
To get the whole field F2%, simply average all stems’ F2%.
3. As
soon as crop fields reach 40% F2, wild blueberry plant tissues, such as fruit
buds and leaf buds, are at risk for disease infection if environmental conditions
favour mummy berry cup development and spore transportation& infection.
4. Once
fields reach more than 40% F2, fungicide protection on the buds is recommended before
forecast wet periods or shortly after an infection period.
5. Most fungicides provide 7-10 days of protection windows. A second application might be required if the infection condition continues.
6. Fungicide
selection: Before developing your fungicide program, please obtain your
processors’ chemical approval list for the season. Perennia’s online pest guides can help you narrow down products for specific requirements: https://www.perennia.ca/online-pest-management-guide/.
A PDF version of the wild blueberry pest management guide is available under
this link: https://www.perennia.ca/wp-content/uploads/2025/03/wild-blueberry-weed-insect-disease-2025.pdf.
Figure 2. Wild Blueberry Fruit Buds in F1 and F2 stages.
The next update will be provided before this weekend. The forecast is calling for a rainy weekend, which could create a potential window for monilinia blight infection for many areas.
Hugh
902-890-0472
hlyu@perennia.ca