Hi,
everyone
Berries
are ripening quickly. From weather station data, personal observations, and
growers’ feedback, the ripening % is from 50% to 85%, depending on your area
and field conditions. It is an early harvesting season. The earliest areas in
the province are looking to begin harvest on August 1. Before that, we still
have a few obstacles to address, especially Spotted Wing Drosophila (SWD) and
Blueberry Maggot!
In this post,
I will focus on:
-
Nova
Scotia GDD and Soil Temperature Updates
-
Wild
Blueberry GDD and Crop Stage Updates
-
SWD
and Blueberry Maggot Management
Nova Scotia GDD and Soil Temperature Updates
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to July 22 for the past 17 seasons. Provided by Jeff Franklin (AAFC Plant Physiology).
As indicated in Figure 1, this season’s growing trend continues to be ahead of the provincial averages. This information also explains why we are calling for an early harvest compared to the previous years. From Jeff Franklin’s comments: “This trend is expected to continue so we may finish July with the highest accumulated degree days on record.”
Higher than-average
temperatures could contribute to higher and more stable soil temperatures. In
Figure 2, the current season’s soil temperature (red line) was above the
10-year average since July. Warm soil temperatures could expedite berry
ripening and insect infestations.
Figure 2. Kentville Research Station Soil
Temperature
Wild Blueberry GDD and Crop Stage Updates
Let’s
take a look at 15 weather stations’ GDD accumulations in different wild
blueberry regions and their ripening status.
The
average for all 15 stations is 1407 GDD (Figure 1). Some of the earliest areas
in the Southshore, Hants, Westchester Station, Parrsboro flat, Newville Lake regions
are looking around 70-85% ripening, which will be the first few areas to begin
harvesting in NS. Thus, we are looking about 50-85% ripening across the province,
depending on your situation. Figure 4 is a quick sheet to show last year’s ripening
% and GDD numbers, which can serve as reference points to predict this year’s
harvest schedule. Around 1700 GDD, crop fields could reach around 90% ripening
and also be marked as the harvesting point if growers decide to.
Here
is another quick tip if you are trying to calculate how many more days before
harvesting. The average daily GDD accumulation in July is around 20 GDD, which
means this time of the year we are gaining about 20 GDD daily.
Figure 3. Wild Blueberry GDD_ April 1 to
July 23
The latest
GDD summary is also useful for sprout fields and their management. All sprout
fields in NS are looking above 90% tip die back. Please don’t forget your leaf
disease management. Ideally, one application should be done pre-harvest. A
second application might be required if wet conditions develop in the late
summer.
Figure 4. Wild Blueberry Ripening %
and GDDs (based on 2023 season data)
SWD and Blueberry Maggot Management
We are in
a very high SWD and maggot pressures season. The key driver is the weather, and
berries ripen earlier, which serve as early food sources for emerging adult
insects.
Since the
beginning of this spring, the soil temperatures have been above the provincial
average for the most of time in this growing season, especially in March.
Higher soil temperature is favored by insect eggs as they can emerge and
develop early.
From field
reports, we are seeing early captures and higher numbers of adults in traps. Growers
are encouraged to put traps out to monitor. A lot of industry partners are
working together to share their monitoring information.
An early first
insecticide application might be needed in the next few days for many growers. At
this point, I would encourage growers to develop a management plan. Please also
double-check with your processors regarding their approved insecticide
products. Please continue to monitor for the next few weeks.
Lastly, I
want to share some information about SWD and Maggots and I hope they are
helpful.
SWD-
Perennia: https://www.perennia.ca/wp-content/uploads/2020/02/SWD-factsheet_March2020.pdf
SWD-
UMaine: https://extension.umaine.edu/blueberries/factsheets/insects/210-spotted-wing-drosophila/
Blueberry
Maggot- UMaine: https://extension.umaine.edu/blueberries/factsheets/insects/201-monitoring-for-the-blueberry-maggot/
Blueberry
Maggot- NB: https://www2.gnb.ca/content/dam/gnb/Departments/10/pdf/Agriculture/WildBlueberries-BleuetsSauvages/C230e.pdf
Have a great harvest season!
Hugh