Hello, everyone
The last few days’ cool temperatures slowed blueberry
development, especially in crop fields with early flowers. This week, the
slower bloom growth may delay beehive placement for some blueberry growers and
beekeepers. Temperatures are rising, and it is forecast to be a clear and warm
week after this weekend. If growers use bumble bee boxes in crop fields, they could
be beneficial this spring, especially during this week’s cool weather. As we get
into the bloom period and pollination season, crop stages could change rapidly
daily. The weather during bloom periods also contributes to pollination
efficiency and yield potential, including frost damage to open blooms.
In this blog post, I would like to share some information
to help with your field management and scouting in the next few weeks, including:
1. Blueberry
frost risks
2. Damage
symptoms from blueberry diseases and frosts
3. GDD
and wild blueberry crop stage updates
Blueberry Frost Risks
As we approach early
flowering, spring frost can pose a severe risk to blueberry blooms if low
temperatures occur in crop fields for a considerable amount of time while there
is a high percentage of open flowers. Figure 1 shows the minimum tolerated temperature
of different blueberry bud and flower stages. When blueberry plants have fully
open flowers and fields have temperatures of -2.2 °C or below, it could cause
permanent and destructive damage to flower structures and impact yield potential,
particularly if the cold period is longer than 3-4 hours.
An easy way to monitor
field temperatures during the bloom period, especially after a frost event, is to
use Perennia’s Farm Data Tools, where you can find the Farm Weather Map to see
over 100 weather stations in NS. This season, we also added many weather
stations from NB.
https://www.farmdatatools.perennia.ca/.
Figure
1. Blueberry Frost Risks
Damage Symptoms from Blueberry Diseases and Frosts
We are still in the blight
season, especially with Monilinia Blight secondary infection and Botrytis
blossom blight. In this week’s field scouting around the Colchester area, I
haven’t discovered Monilinia Blight symptoms in crop fields yet. As we enter
bloom season, Botrytis Blossom Blight is another significant blueberry disease
to monitor and manage, especially if crop fields are in susceptible areas with
wet conditions. As I mentioned before, low temperatures could also damage blueberry
flowers.
Figure 2 is a valuable resource
for distinguishing different symptoms caused by blueberry diseases and frost
damage in wild blueberries.
Figure
2. Photo and information credits: UMaine Wild Blueberry Research and Extension
Group
Wild Blueberry Weather Station GDD and Crop Stage Updates
We have selected 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
3. Selected Wild Blueberry Weather Stations and GDD Updates (April 1- May 21)
Table 1. Wild Blueberry Weather Stations and GDD Updates
(April 1- May 21)
