Thursday, September 14, 2023

                                         BLUE FOCUS NEWSLETTER- Fall Edition, 2023

(Perennia’s Wild Blueberry Newsletter)



Hello everyone,


Harvesting season is pretty much over for Nova Scotia wild blueberry growers. This newsletter’s cover photo is to acknowledge all the hard work and extra hours that growers put into harvesting. It has been a challenging year and challenges never stop.

As most of you are wrapping up the harvesting season, you are probably also thinking ahead of fall field management and inputs for next year. We will talk about some fall management recommendations in this newsletter. It is a hard year to guess and confidently say the rough number on yield in different regions and I will share things I know. We are running into the fall season and it means meetings and workshops will start to pick up. Please keep your eyes on the Perennia wild blueberry blog, blog calendar, Perennia event page, WBPANS newsletter and other agricultural-related organizations' event pages.

Have a great fall season and hope to see you in the coming meetings.

Stay safe!

Hugh Lyu

Wild Blueberry Specialist, Perennia; 902-890-0472.

September 14, 2023


Table of Contents: 


Wild Blueberry Industry Production Updates- 2023

Weather Tools

2023 Season GDD Update

Upcoming Management Recommendations (FALL)




Wild Blueberry Industry Production Updates- 2023


As an industry, we are looking at a lower total yield, compared to 2022 (351 million lbs), but we are likely to reach the 300 million lbs line.  


Nova Scotia:

The yield expectation for NS is around 40-45 million lbs in 2023. This is down from last year's 57 million lbs. Our recent 5-year average is 40 million lbs so I think we will be around our average but down from 2021 and 2022.

Our challenge this year is the weather, especially excessive moisture that started the first day of June and continued to be wet most of the summer.

 For more information about why NS has lower yield this year, go to my last blog post: 

Prince Edward Island:

-          PEI had below than average snowfall last Winter and a bad cold snap in early February which caused some winter damage

-          The early bloom weather (late May/ early June) was not ideal for pollination as it was cold and wet

-          The weather cleared up for the latter half of June

-          The rainy pre-bloom and bloom season increased fungal disease pressures

-          There was adequate heat and rain throughout the remainder of the season resulting in good fruit set and plump berries

-          It was rainy throughout the harvest season which caused issues but there were enough pockets of sunshine to get the crop harvested

-          Overall, the expecting an average yield (20-25 million lbs).


New Brunswick:

-          There was little winter damage, some localized damage. Very little incidence of blight.

-          Early bloom weather was decent for early fields, but late May into the first 10 days of June, cool with periods of rain, although, fruit set was decent.

-          The rain through July and August helps size up fruit but creates harvesting challenges with wet fields.

-          Overall, growers are commenting that the crop is average or slightly below, not as good as last year. The Provincial average is roughly 65 M lbs and would be estimated that the crop is likely between 60 and 65 M lbs.



-          Quebec observed localized winter damages in some fields in the spring.

-          Mid-May, frost occurred during the bud break. It created localized damage, especially in the lower parts of the fields. There were cold nights in June but, the temperature did not drop below -2 Celsius and only for a short period at once.  

-          Weather during pollination was good and hives were strong.

-          Quebec growers noticed significant but localized hail episodes. Some fields had lost 100% of their fruits.

-          In July and August, they had a lot of rain so drought wasn’t a problem.

-          The crop will be higher than average with an estimate of 110 M lbs.


Maine is looking close to 2022 yield (80 million lbs) and Maine's 5-year average (74 million lbs).

Maine also faced some weather event challenges as well, like frosts. The rain arrived after pollination and the rain also helped to size up berries, in a perfect time and a good amount.

During harvesting, it was wet in Maine but Maine's soil typically is more well-drained so harvesting continued.


Table 1 Wild Blueberry Yield Across Regions (in million lbs)

*It is a hard year to guess and I don’t have enough time to get back from all other regions. Once I know, I will update this table immediately.








5-year average





















2023- prediction









**Source: Wild Blueberry Market Info Bulletin- Maritime edition- August 2023.


Weather Tools


When it comes to fall, there is one thing that wild blueberry growers care about more than others and that’s the field soil temperatures. Of course, only if you need to apply Kerb. We will start reporting soil temperatures from 44 out of a total of 55 weather stations. We will never stop talking about the weather, so this weather tool summary section is to show you the weather tool that wild blueberry growers need in the fall.


Field soil temperature:

Soil temperature is one of the key factors for a successful Kerb application and hair fescue control. We recommend growers wait until the soil condition is cool enough but before frozen to apply Kerb. The optimum soil temperature is between 0 to 10 degrees Celsius.

To check soil temperatures from 44 weather stations located in wild blueberry fields across NS, go to the weather page of the wild blueberry blog:


Click on the weather stations you want to check and continue to click on the Live Data Link. Once you are on a different page, scroll down to the bottom and find this information “Temperature Probe”.



Perennia’s Farm Data Tools Platform:

The “Farm Weather” page is still a good site to quickly look at live weather data, and calculate GDD and there is an option to download weather data.


Cape Breton Mesonet: If you need to look up more weather information in PEI and NS, this site covers a lot of locations.



2023 Season GDD Update

Now is not an exciting time to check GDDs, but I want to show you quickly how many growing degree days have been accumulated since April 1.

On September 13, 2022, the average accumulated GDD from wild blueberry weather stations was 2400, and V.S. 2337 in 2023. Because of lower and cooler temperatures in the last little while, things are moving slower. We are in a similar trend as last fall. It is a concern on if blueberry ground will be dry enough for fall mowing and herbicide application.




Upcoming Management Recommendations (FALL)


In the fall, mowing harvested crop fields and applying herbicides are two important jobs in wild blueberry production.


Pruning wild blueberry fields: we don’t talk about this often, but over the last two seasons, I have noticed some field problems related to mowing. Here is a very good factsheet on everything you want to know about pruning wild blueberry fields, produced by the University of Maine.

Fall weed management in wild blueberry fields:

Because of the excessive rain we got over the summer, weeds grow even more, especially in your crop fields. Some of you probably already documented what you saw when you were in the harvesters, I encourage you all to see what weeds you need to control and start to make a plan.


Here is an article about fall weed management. In this article, control times are broken down into post-harvest in September (right now), post-harvest before mowing (September and October), and post-harvest after mowing (November and beyond if weather conditions cooperate). I also mentioned weed species to target in the fall and herbicides you can use but please follow guidelines closely as fall herbicides are also sensitive to temperatures, both in the air and soil.

Link to the article, Fall weed management in wild blueberry production:




Some important announcements and updates that you might have heard already, but things to do in the fall and winter when you looking for things to do.

1.       A good time to share this document just in case you didn’t receive NSDA’s newsletter. How to prepare for a storm: Storm Preparedness Checklist- by NSDA:


2.       AgriStability Update


Nova Scotia farmers affected by this year’s extreme weather events can still receive assistance under the AgriStability program, even if they did not previously enrol. AgriStability supports farmers experiencing a large decline in farm income by providing protection for income losses of more than 30 per cent.

Farmers who did not previously enrol in AgriStability for 2023 can now participate in the program as late participants until December 31, 2024. For more information, please visit



3.       NSDA Programs: Again, there are still programs available through NSDA.


4.       NSFA- Nova Scotia Farm Discovery Tool. I recently found out about this useful tool from NSFA. It will automatically generate a resource list based on your areas of interest and problems to solve. Check it out:





Meetings and workshops are starting to pick up. Please check regularly on the blog event calendar page ( where I update regularly on events related to you.

Here are a few things coming up in the next few months:

1.      NSFA: Efficiency Symposium, October 2nd from 9:30 am- 2 pm at the Inn on Price in Truro. Event details and registration information can be found in this link:

2.      WBPANS Annual General Meeting, November 16 and 17, details to follow. 

Why We Have Lower Wild Blueberry Yield in 2023?

Wednesday, September 13, 2023

I was going to make this post earlier but was waiting to gather more information from field visits and growers. Most of you should be done harvesting by now and start to look at numbers on receipts. Without looking at receipts, it is probably a known feeling about yield reduction during harvesting time. I heard yield reductions ranging from 30% to 60% from different growers. A single event is unlikely to cause more than 50% yield loss (but still possible, like the 2018 frost), but we have a lot of events happening this season. Each of these events could contribute to a 10-15% yield reduction, and it also depends on where your fields are located and what kind of microclimate zone you are in. This year, the wild blueberry crop stages, pollination weather and management activities are very different from region to region. It is an interesting year for sure.

After visiting fields during harvesting season and talking to growers and combining information we know throughout the season, I like to summarize all the negative factors I know that contributed to yield losses this year.

If you have additional points to share, please contact me.


Winter Weather


-          February 2023 “Polar Vortex”


As many of you already submitted the “Polar Vortex” information related to wild blueberries, it is getting clear that this event would have caused damage to blueberry overwinter stems, internally and physiologically. Due to the lack of snow coverage in fields, and the extremely low temperatures for a couple of days (Feb 3-5), stems and fruit buds could have been damaged or with lower vigour for further development. Stems could also have a lower tolerance to cold temperatures, disease, and insect damage. However, if you are in a more protected area or with snow coverage in whole or parts of fields, you wouldn’t experience a higher loss from the “Polar Vortex”. That’s one of the reasons why within the same field, growers had some very good patches mixed with very poor patches (barely any berries) (Figure 1).


Figure 1. A blueberry patch with good and bad sides


According to this Quebec wild blueberry factsheet, overwinter rhizomes and stems will get damaged when temperatures fall below -25°C. Around this temperature, sufficient snow coverage is needed to protect plants and unfortunately, we didn’t have that condition for most of the fields. When we checked all on-farm weather stations in NS, the minimum recorded temperatures were below -25°C for most of the wild blueberry stations in the northern region. When considering wind effect (wind chill and wind speed), the damage level would be higher. Figures 2, 3, and 4 show the minimum temperature, min wind chill and maximum wind gust from weather stations. Click on each photo to see more detailed numbers. 


Figure 2. Min Temp – Feb. 4, 2023 (NSDA/Perennia Weather Station Network, 96 Sites)




Figure 3. Min Wind Chill – Feb. 4, 2023 (NSDA/Perennia Weather Station Network, 96 Sites)




Figure 5. Max Wind Gust – Feb. 4, 2023 (NSDA/Perennia Weather Station Network, 96 Sites)


-          Below-average snowfall


We knew the lack of snow coverage in fields, which resulted in a lack of protection for plants to fight cold and extreme temperatures. The amount of snowfall, according to the National Agroclimatic Risk Report, was below average and some areas of the region reported a record-breaking lack of snowfall.


-          Warmer temperatures- not enough chilling hours for wild blueberry plants


Before we talk about how warm this past fall and winter were in NS compared to the more normal temperatures we were supposed to get, let’s talk about chilling hours for blueberries.


Chilling requirements for blueberry plants:


Blueberry plants require a period of cold weather during the winter months, known as chill hours or chilling requirements, to successfully produce fruit in the summer. This need for chill hours is a biological adaptation that helps blueberry plants synchronize their growth and fruiting cycles with the changing seasons. Adequate chill hours are important for dormancy regulation, bud development, timing of flowering, as well as fruiting and pest control.


We have limited information on wild blueberry chilling requirements in terms of numbers, so we use numbers from highbush blueberry production to interpret the warm temperatures we got in the fall and winter and their effects on blueberry growth and yield potential. The traditional definition of a chill hour is any hour under 7.2 °C. The mid-range chill hour requirement for highbush blueberry varieties is between 500-550 hours. The wild blueberry is a high-chill plant, therefore it requires higher chill hours. In other words, wild blueberry plants need to get at least 500-550 chill hours for a successful fruiting year.  


If crops do not get enough chill hours, you may have to deal with problems of delayed foliation, bare shoots, weak bud break, and even flowers that just fall off (shorter flower pollination life), fruits that never develop, increased risk of pests and diseases, or poor-quality fruit. One thing I heard commonly from growers is that it seemed that there were a lot of blossoms (even more than ever), but there were no fruits. The chilling requirements for blueberries explain part of the reasons for growers' observation.


I wish I could present you with data and numbers, but I am waiting for those numbers to come. I hope to update you on this in the fall meetings. However, just based on how we felt in the fall, experienced a warm January. I remember some growers applied Kerb at this time.


In normal years, regions in NS could start counting chill hours as soon as we hit the first fall frost, but this winter, the date to count consistent chill hours was much delayed. In the fall, if temperatures drop below 7.2 °C for a few days, but suddenly back up to high temperatures, the process can be reversed and we get a new start date and chill hours counting starts over again.


The remaining factors are all related to rain and wetness.



Here is a nice graph that I got from CBC which shows the amount of rain received in most wild blueberry fields in NS was 600- 800+ mm. This is 2.5 times more than the average. Those rain events we got this year either showed up at a bad time (pollination period), brought higher than the average amount of rain, or had the intensity of rainfall in a short period. A lot of times, we got them all this year.


Weed competition


Weed management starts early but runs for the whole year. It is a never-ending task. Weeds are plants and watering plants makes them grow faster and more. Herbicide application requires relatively dry conditions during spraying but it will get benefits for some moisture in the soil to improve herbicide efficacy after spraying.


-          Pre-emergence herbicide application

This point is not related to this year’s crop directly, but it might impact next year’s crop if poor weed management was performed this year.

Although April and early spring were fairly dry, we got a break from the April drought at the end of April. I followed on fields owned by growers who consulted me with blueberry emergence GDD and progress, a lot of fields in the early Cumberland areas can start pre-emergence herbicide as early as the last week of this April. I also noticed fields that received herbicides on time before the rain had better weed control when fields were visited again in mid-summer.

A lot of growers are still relying on their memory to plan for spring herbicide timing which might put them in a bad position. We had a very windy spring and early summer. On a lot of days, the wind speed and gusts were above 30 km/hour. The first two weeks of May were the period when I knew most of the growers were rushing to apply herbicides but also wanted to do fungicides for mummy berries. We didn’t get mummy berry infection this year because it was dry during early- mid-May. This is good for disease control but for herbicides, if the soil were dried up quickly in the first few inches of the soil where are wild blueberry root and rhizome system located, as well as most of the common weed species growing zone, the control result could be reduced.


I also visited some sprout fields treated with Velpar (hexazinone) this spring, and the control result was disappointing. Please remember, that we have been using Velpar or Pronone since 1982 and in 40 years, the repeated use of Velpar resulted in herbicide resistance in many weeds, such as Red Sorrel and Hair Fescue. If you continue to use Velpar but in mid-summer, if you still see a lot of weeds in your sprout fields, it is a good sign that you need to switch to different products based on the weeds you have.


-          Weed growth in the summer- crop fields


Herbicide application in crop fields is limited due to fewer products to use and the window to apply herbicides is short. This season, the condition is favourable for weed growth which increases crop and weed competition.




This year, we had higher-than-normal botrytis blossom infection across the whole province. It didn’t look like the damage was significant or in a higher percentage yield reduction range, but those infected fields and clones can expect 5-10% losses.

Several factors contribute to higher botrytis infection. During the bloom period, rain never stopped in June. Excess moisture will increase disease infection. Even though you are not in a foggy area or botrytis-prone area, the wet conditions in every field make plants susceptible to infection. Weather conditions (high wind and rainy days) also prohibited spraying fungicides so many crop fields were under wet conditions without fungicide protection.


Pollination Weather


It was wet and cold during pollination and bloom period. Some early fields had a few good pollination days before June and some fields were lucky to have better pollination results either because of good weather or higher pollination input. Overall it was a poor pollination year for wild blueberries. The percentage of yield losses due to poor pollination was variable from region to region since the weather was different in different fields. The level of pollination input also has gaps between farms.


Excessive Wild Blueberry Vegetation (leaves) Growth in Crop Fields


A lot of you probably noticed that there were new blueberry leaves formed and continued to grow before harvesting. This is more common and severe to see in fields that receive high rates of granular fertilizer and extra liquid fertilizer in both years. The wetter soil creates a good environment to make soil nutrients and applied fertilizer more accessible for plants, including blueberry crops and weeds.

When nutrients and energy are used to produce more vegetation, the process of fruit development will be affected. Ultimately, fewer berries are formed, and growers experience significant yield reduction. The winter weather conditions and excess water and nutrients for plant growth changed blueberry plants' physiological development.


More water after the fruit development stage


During the fruit development stage, it was one of the good windows this year for wild blueberries. There was enough moisture and good temperatures, so we observed bigger berries and crop fields started to turn in a better direction. However, as we headed into the harvesting season, water started to create problems.

-          Berry losses and quality

Too much water also made berries split easier which reduced yield and fruit quality.


-          Harvesting weather and ground

During harvesting, the weather mixed a few periods of rainy days in between which caused delays to harvest berries. Roads in fields were soft and might have been washed out during flood events. Wild blueberry fields’ ground was soft which reduced harvesting speed. Harvesters and other machines’ tire tracks caused damage to the ground and potentially, those areas will become wet spots in the future if not fixed.


What about this year’s sprout fields?


Similar to crop stems, sprout stems also continue to grow vegetatively (more young leaves are produced). This delays plants’ tip dieback (stopping point for blueberry vegetative growth), and next year’s fruit bud forming and development. I also noticed fewer fruit buds were formed compared to previous years. There are still a lot of time and unknown factors that could affect next year’s crop and this is the biggest one I observed during farm visits.

Plant vigour can also be affected by excessive moisture and water-logged soils and this might hurt next year’s yield potential.


Leaf Diseases Management Reminder and Phomopsis Stem Blight (Canker)- check your fields!

Tuesday, August 8, 2023

 Good afternoon, everyone


As we get further into the season, a lot of other important wild blueberry diseases start to show symptoms, such as Septoria leaf spot and leaf rust, which are two very important leaf diseases to manage in wild blueberry production. These two publications are good references to read. 

Leaf Diseases Management Reminder


NB: Leaf Diseases of Wild Blueberry

AAFC: Diseases of Lowbush Blueberry and Their Identification


Growers should have at least one leaf disease fungicide application in sprout fields before they start harvesting in crop fields. Do we need a second leaf disease application and when is the latest the application can be made? It depends on the weather. If August will be wet and humid (like in 2021), a second leaf disease application might be needed. This year’s weather seems to be heading in that direction so growers should monitor their sprout fields and if early defoliation is observed in patches, then a second leaf disease spray should be planned. Ideally, a second leaf disease spray should be made before Mid-September, otherwise, the control effect will be reduced.


Leaf Diseases Management Reminder Phomopsis Stem Blight (Canker)- check your fields! 

In normal dry years, we rarely see other low-important diseases in wild blueberries, such as Phomopsis stem blight (canker), because they affect only a few stems which are hard to see if you don’t look carefully.

Phomopsis stem blight, in other years, you would just see one or a few stems inside clones, like this photo below and it is not severe enough to have a concern. This year, as we all know, is a wet year. The amount and intensity of rainfall not only wash out roads in fields but also contribute to pest development.  

The infected stem tissue is reddish brown and dead reddish-brown leaves (more photos below). Phomopsis canker’s disease cycle has not been extensively studied in lowbush blueberries, but we understand that the pathogen may spread by water-dispersed spores. The amount of water sitting in fields, especially in low and wet spots, with splashes caused by intensive rainfall periods, is helping the pathogen to move around and infect nearby stems. Eventually, under this year’s rainfall events, this year’s phomopsis canker disease is affecting large areas in wild blueberry fields. I have seen and gotten reports from growers about this disease. The infected areas might look like sprayed with roundup, but if you look closely at the ground, you will find brown dead stems.

I found more large infected areas in sprout fields than in crop fields. Those badly infected areas are in water-sitting spots.  

If you happen to run into your fields and see an empty patch of wild blueberries,\the area might likely have been infected by Phomopsis canker. 

Some of the fungicides that we use in this industry will also offer some benefits for phomopsis canker, such as Bravo, Quilt, Pristine and Merivon, so I don’t think an additional application for this disease is needed. Wet and low spots are normally the trouble areas.

Burn running is likely beneficial for disease control as it reduces infected plant material.