Hello everyone,
It has been a wild week with rain and wind across Nova
Scotia. We are now entering the active wild blueberry growth stage, with quick bud
break occurring in many crop fields after the last two days’ high temperatures.
At the same time, growers are facing challenging spraying conditions while
trying to understand variable crop development this spring.
Carryover effects from the 2025 drought continue to
influence crop fields. Many fields show variable numbers and sizes of fruit
buds, resulting in uneven bud development. The spring conditions have also
resulted in slower crop development this season, approximately 1 week behind
2025 in many areas. The last two days’ high temperatures contributed to a
significant jump in crop stages, as measured by F2 percent, marking the
beginning of this year’s blight management.
Below are several highlights to support your planning
over the next few days.
1. Sprout Fields — Pre-Emergence Herbicide
Applications
It remains a good window for pre-emergence herbicide
applications in sprout fields.
Herbicides such as Chikara, Ignite, Spartan, Involve,
Velpar, and Sinbar can still be safely applied across all production regions
through this week and into mid-next week, before next weekend.
If applications have not yet been completed,
prioritize sprout-field herbicide treatments over the next several days. From a
weed-growing perspective, the main weeds, such as sheep sorrel and hair fescue,
have been actively growing since early spring.
2. Crop Fields — Monilinia Blight (Mummy
Berry) Management
Fungicide products such as Proline or Soratel should
be timed carefully based on the crop fields’ bud development and weather risk.
a. Bud Susceptibility
Blueberry fruit buds become susceptible to Monilinia
blight once buds begin to scale and move beyond the F2 stage (Figures 1 and 2).
b. When to Plan the First Blight Spray
·
When crop fields reach approximately 40%
F2, infection risk increases significantly.
·
Fungicide applications should be planned
at this stage in coordination with forecast weather conditions.
Using the Wild Blueberry Growing Degree
Day (GDD) model:
·
160 GDD serves as an important alert
point.
·
Once local weather stations exceed 160
GDD, growers should monitor fields closely (Figure 3).
·
After this threshold, a fungicide
application may be required within only a few days, depending on rainfall and
infection risk.
c.
Regional Development and Current Blight Risk
(Table 1)
Still Early for Blight Management
·
Pictou
·
Guysborough
·
Antigonish
·
Cape Breton
Most fields in these regions remain below critical
infection risk.
Cumberland and Colchester Counties
• Early-developing or
lowland fields have reached approximately 160 GDD and more than 40% F2
development. For these early fields, where F2 percentages are high or crop
stages are more advanced, fungicide applications should be planned before the
Sunday–Tuesday rain period, or applied shortly after next week’s wet conditions
if spraying opportunities are limited.
• Late-developing or
higher elevation fields are progressing more slowly; however, following the
Sunday–Tuesday rainfall events, these fields are also expected to enter the
infection risk stage. Growers should therefore plan fungicide applications next
week as conditions become conducive for disease development.
Field Variability Due to 2025 Drought
We are observing and hearing variability within
fields:
·
Differences in stem length
·
Variable fruit bud numbers
·
Uneven bud size, vigor, and bud break
rates
These conditions reflect differences in stored plant
reserves following last year’s drought.
As a result:
·
Stronger buds are advancing quickly.
·
Smaller or weaker buds are breaking later.
·
Crop development may appear uneven across
individual fields.
Field
scouting is essential this year. Do not rely solely on regional timing — check
your own fields carefully.
Upcoming Weather Considerations
A weather system forecast from Sunday through
Tuesday/Wednesday is expected to bring significant rainfall.
Final Thoughts
This season continues to highlight how strongly
previous-year stress and current weather conditions influence wild blueberry
development. Careful scouting, flexible spray timing, and attention to field
variability will be especially important in 2026.
Figure
1. Susceptible Fruit Bud Periods
Figure
2. Wild Blueberry Fruit Bud F1 and F2 Stages
Wild Blueberry Weather Station GDDs and Crop F2 Stage Updates
Figure
3. Accumulated Growing Degree Days (April 1–May 7, 2026)
Figure
4. Wild Blueberry F2% and GDDs
We will continue
providing updates on F2 stage percentages across different production
regions as information becomes available throughout the season.
Table 1. 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 |
|
|
Halfway River |
>40% F2 |
|
|
|
|
|
|
|
South West Nova Scotia |
|
|
Weymouth |
>75%F2 |
|
Caledonia |
>70%F2 |
|
Annapolis |
>55%F2 |
|
|
|
|
Hants County |
|
|
|
|
|
Halifax County |
|
|
|
|
|
Guysborough County |
|
|
|
|
|
Colchester County |
|
|
Murray Siding/ Truro |
>40% F2 |
|
Belmont |
>40% F2 |
|
Debert |
>40% F2 |
|
Londonderry/ Baseline Rd. |
>40% F2 |
|
Greenfield |
35% F2 |
|
Camden |
>40% F2 |
|
|
|
|
Pictou and Antigonish County |
|
|
|
|