2022 Updates and Seasonal Outlook for NS_ June 10

Friday, June 10, 2022

2022 Updates and Seasonal Outlook for NS_ June 10


2022 Degree Day Accumulations and Crop Update

Table 1.0 Degree day accumulations as of June 6, 2022.  All data are taken from the Kentville weather station, based on a start date of March 1, and calculated using the single sine method.






5 year average

10 year average

Plant development (Base 5ºC)







Insect development (Base 10º)







Here is a summary of 2022-degree day accumulations from the Kentville weather station. This summary gives us an idea of where we are at in terms of this season’s growth and development. In NS, we are above both 5-year and 10-year averages (383.1 GDD vs 342.9 GDD and 360.2 GDD). 

Here is another GDD accumulations update from wild blueberry weather stations:

Figure 1. Wild Blueberry GDD Summary- June 9, 2022

The average of GDD accumulations from all stations was 591. As we have many different growing regions with different development stages in the province, it is hard and unrealistic to give a solid statement about the whole province’s crop development. However, in general, we are looking at more than 50% to 90% plant emergence in sprout fields in NS. In fruit fields, we are at 90% open flowers, with some early to middle fields getting to more than 50% petal fall (pin head). Even late fields, such as Advocate and Cape Breton Island, fields are in the early to middle flowering stages.

As I mentioned in the last update, we observed low diseases infection for this season due to the dryness of the weather.


Weed Management in Sprout Fields and Use of Callisto 480 SC (mesotrione)

During this time of the year, activities can be and should be done in sprout fields including weed management. Growers can pull or cut weeds above the blueberry canopy before they go to seed or cut weeds to the base. If it is necessary, some selective post-emergent herbicides, such as Callisto 480 SC (mesotrione) can be used to control a wide range of broadleaf weeds.

Here is a little bit of information about using Callisto to achieve effective weed management.

Blueberry growers have observed more crop injury when applications are made under hot and/or humid conditions or when the crop is stressed from flooding. The injury is most visible where excessive rates have been applied, such as sprayer overlaps. If heavy rain is expected within 48 hours, an application should be delayed. For improved crop safety, make applications under cooler conditions (early morning or evening) or when daytime temperatures are below 21 °C.


Pollination and Determining Percent Fruit Set in Wild BLueebrry Fields

In general, genetic factors of wild blueberry plants play a critical part in affecting pollination, other factors also contribute to and influence the overall pollination rate. Those factors include weather, plant vigour, distribution of clones and the population of pollinating insects. Because there are so many factors to affect pollination, it is not realistic to achieve a high % fruit set of 75 to 100%.

In general, pollination rates of 40 to 50% are considered very good, while 50 to 60% would be considered excellent. If the rate is below 30%, this shows the pollination force is too low.

Growers will get the benefits to understand and know how to determine the % fruit set. When growers know their % fruit set, they will be in a better position to understand their field and productivity, as well as help them to improve their production practices.

There is a great factsheet from the Department of Agriculture in NB that talks about determining % the fruit set in wild blueberry fields. Here is the link to this factsheet, but you can read the information below to get quick access to this information. https://www2.gnb.ca/content/gnb/en/departments/10/agriculture/content/crops/wild_blueberries/determining_percent_fruit_set.html



Information from the factsheet:

When you sample a field, you should sample ALL the field. Since conditions may vary from field edges to field centres, you will need to sample both types of areas unless you are trying to compare them. If you sample a big area, then you will need to take more samples. Fifty to one hundred samples seem to be adequate for a twenty acre field.

Walking your field during early to mid-bloom, you will take RANDOM samples by crossing the field back and forth in the shape of a "W", as you would for soil sampling. At each one of the sites at which you stop, you should sample in the following fashion:

  1. You will be following the progress of one stem at each sample site. At each site, drop a pen or a similar small object and sample the stem which is located closest to where the object falls. This will keep your sampling random. You can identify the stem by tying a piece of coloured synthetic string loosely to the stem, below the flower stalk (known botanically as a raceme). Place a brightly colored flag right next to it, so that you can locate the general location of your sample stem. Identify the sample number with indelible ink on the flag, and record this number and the information described below in a log book.

Figure 2. An example of tagging and flagging study stems


When sampling at early to mid-bloom, you would be counting and recording the TOTAL NUMBER OF FLOWER STRUCTURES which are found on the sample stem (this includes unopened blossoms, open blossoms, and blossoms which have lost their petals).

  1. Prior to harvest just when most of the fruits have turned blue, return to the same sample and count the TOTAL NUMBER OF BERRIES which will produce a harvestable fruit. Do not include the "pinheads" (those fruits which have larger crowns than berries).

  2. Use the information from (1) and (2) to determine the percent fruit set for the sample site, and then combine the information to learn the average percent fruit set for the field.

Here is an example:

  • From section 1. The TOTAL NUMBER OF FLOWERS e.g., 70 unopened buds, open flowers, flowers without petals
  • From Section 2. The TOTAL NUMBER OF BERRIES e.g., 35 harvestable berries
  • PERCENT FRUIT SET = (35 / 70) x 100 = 50%

To calculate the percent fruit set for the field, add all the sampling sites and divide by the number of sites. If the differences between the sampling sites are very big, you might consider taking more samples next year OR you might try and figure out why. Some growers claim to get up to 70% fruit set; so if your figures are really low, you know that the top priority for managing that field is bees.

You can also use this method to calculate differences between your fields or differences that you might have from using or not using hives.



I will issue June’s Perennia Wild Blueberry Newsletter (BlueFocus) early next week. Stay tuned for the issue. We have some updates to share!

Have a great weekend!