This post will focus on frost
and weather updates, botrytis management and pollination.
Frost and Weather Updates
May 30 Frost Damage
Update:
Regarding Tuesday’s (May
30) morning’s frost, I made a summary of minimal temperatures from wild
blueberry weather stations: http://www.novascotiawildblueberryblog.com/2023/05/post-frost-event-summary-may-30-2023.html.
I checked fields in Pictou
(Blue Mt., Moose River and Blanchard Road) where stations reported below -2 c
for about 6-7 hours. Luckily, all fields in those areas were still in the pre-bloom
stage with limited open blooms. I don’t think growers should concern about this
frost.
The next potential frost
is going to be around the full moon (June 4) and here are some words from
weather experts:
“The weather pattern is
most likely going to be a cool and wet one this weekend – all models are
predicting it actually. This means cool
but overcast and light to moderate NE winds.
Temps would likely be in the 5 to 10C range for several days if this
pattern ‘stalls’ which is the current indication. So that’s a saving grace as long as the skies
don’t clear out during the spell of weather.
Even if they did clear out for a short period over the weekend, it could
be brief and the ground should already have moistened up with showers/drizzle.”-
from ECCC.
Most mainland
fields will be in full bloom or in a high percentage of bloom stage (20% and
above) which puts those fields at a greater risk of frost damage. If you are thinking
to apply fungicides (Pristine and Merivon), the most effective window would be
12-24 hours before. Based on this, the time frame (regardless of the rain we
might get this weekend) is Friday to Saturday morning.
Weather Update:
Perennia’s Tree Fruit
Specialist, Michelle Cortens, wrote a summary about this year’s weather, including
GDD and precipitation. https://www.nstreefruitblog.com/2023/05/orchard-outlook-newsletter-vol-23-no-7.html#h1.
This is a very nice information for you as well. Thanks, Michelle!
Content from Perennia’s Tree
Fruit Blog:
2023 Degree Day Accumulations
Cumulative degree days continue to be slightly behind the 5- and
10-year averages for plant and insect development (Figure 1). The lack of heat
equates to plant growth being about 2 to 3 days behind average. The average
temperature for May is 10.2°C compared to the 10-year average of 11.2°C.
Figure 1: Heating degree day accumulations
for plant (above 5°C) and insect (above 10°C) development from March 1 to
May 29 for the past 17 seasons. Provided by Jeff Franklin (AAFC).
·
Approximately 8% less plant development
heat units compared to the 5-year average, and 9% less compared to the 10-year
average.
·
Approximately 22% less plant development
heat units compared to 2022, and 21% less compared with 2021.
·
Approximately 10% less insect development
heat units compared to the 5-year average, and 15% less compared to the 10-year
average.
2023 Precipitation
The Kentville weather station has recorded less than half the
monthly average rainfall at 31 mm out of 74 mm. Jeff Franklin assembled the
total precipitation for the months of April and May, for Kentville, over the
last 111 years and sorted from lowest to highest. The 10 driest years are shown
in Table 1 and 2023 ranks as the 5th driest year.
Table 1: Total precipitation for the
months of April and May in Kentville over the last 111 years, showing the 10
driest years. Provided by Jeff Franklin (AAFC).
Botrytis Management
If you are in
areas where typically more prone to botrytis infection, such as coastal areas, and
wet/fog areas and if your fields are weedy (sheep sorrel is an important host)
with very dense patches, you should consider and monitor the situation for
treatment application. The fungus begins to sporulate at early bloom, so the
best time to apply (if needed!) the first application is when about 30-40% of
the flowers are open. Closed flowers are resistant to infection. A second spray
can be applied about 7-10 days later.
Pollination
Overwinter beehive
health: last I checked with some beekeepers, the winter losses for NS bee hives
were around 15-20% which is still under an acceptable range. Bees survived over
the winter look very good and they gain weight very fast. Up to this point, a
couple of beekeepers are still feeling there is enough nectar flow with the
rain we will get next week, it should be a very positive sign for pollination.