BLUE FOCUS NEWSLETTER- July 2024

Wednesday, July 31, 2024

We are very close to Nova Scotia’s wild blueberry harvesting season. We are experiencing a higher risk of SWD and Blueberry Maggot damage this pre-harvest season. Monitoring and spraying as needed are strongly recommended at this point.

I hope everyone has a great and safe harvesting season! 🫐🫐🫐🫐🫐

Hugh Lyu

Wild Blueberry Specialist, Perennia

hlyu@perennia.ca; 902-890-0472.

July 31, 2024

Nova Scotia Weather Update

Nova Scotia Wild Blueberry Crop Development Update and Management Recommendations

Upcoming Events

Nova Scotia Weather Update

2024 Degree Day Accumulations- Kentville, NS: The degree day accumulations are based on the weather data from Kentville weather station, giving us an overall idea of this production season’s temperature trend in Nova Scotia.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to July 29 for the past 17 seasons. Provided by Jeff Franklin (AAFC).

- The degree day accumulations for base 5°C plant development and base 10°C insect development are ahead of the 5- and 10-year averages (Figure 1).

Table 1.0. Degree day accumulations as of July 29, 2024. All data are taken from the Environment and Climate Change Canada weather station located at the Kentville Research and Development Centre. Calculations are based on a start date of March 1, and calculated using the single-sine method.

Category	2021	2022	2023	2024	5-year average	10-year average
Plant development (Base 5ºC)	1179.2	1164.3	1131.2	1196.8	1117.0	1103.7
Insect development (Base 10º)	682.0	671.7	671.7	706.0	647.0	638.1

Nova Scotia Wild Blueberry Crop Development Update and Management Recommendations

From the wild blueberry stations, we have 15 stations across the province, and the GDD accumulations from April 1 to July 1 are shown in Figure 2. On average, we are looking at 1566 GDD. From our past study, the preliminary results suggest that commercial wild blueberry harvesting can start after 1700 GDD (90-95% ripening). However, we are experiencing an early spring which means that plants have a longer and earliergrowing season. Growers might experiencing early harvesting in 2024.

Figure 2. Wild Blueberry Weather Stations GDD Accumulation from April 1 to July 31, 2024

Upcoming Management Recommendations

1. Insects, trapping for SWD and Blueberry Maggot:

To trap and understand SWD: https://www.perennia.ca/wp-content/uploads/2020/02/SWD-factsheet_March2020.pdf.

For blueberry maggot: Yellow rectangles coated with sticky material and an attractive bait are used for monitoring the blueberry maggot. When the first capture is found, it is better to give a few days for more adults to emerge.

Please remember to check the products’ pre-harvest interval (PHI) and check with your processor before you apply products in the fields.

2. Weeds, start to cut above-blueberry canopy weeds to ease the harvesting process. Also, note down what weeds you have at this time. This information is helpful to develop next year’s weed management program.

3. Leaf disease management in sprout fields. Before you start harvesting, you might want to consider spraying chemicals for leaf disease control. It is possible to run into a couple of wet periods in the next two months in our region, which would favor the disease infection. Therefore, it is important to provide that protection to wild blueberry sprout plants, especially in fields have bad disease infection in the past. The ultimate goal for this activity is to keep sprout plants’ leaves on stems as long as possible so bigger and stronger fruit buds can be produced for the next crop season.

Blog Post_ July 23, 2024

Tuesday, July 23, 2024

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