2024 Production Updates and Seasonal Outlook for NS_ 6th Blight Line Post_ May 10

Friday, May 10, 2024


Hi, everyone

We are looking to have some decent spraying weather in the next few days. The next potential long wet period could be mid-next week. Before the weekend, I want to share these quick updates.

Have a good spraying weekend!




GDD Updates_ May 10, 2024



Figure 1. GDD Summary, May 10, 2024

Wild Blueberry Sprout and Crop Development Stages

Sprout fields:

Growers are encouraged to complete pre-emergence herbicide applications as soon as possible.

New blueberry leaf buds are starting to form and in some early areas/fields, leaves are unfolding. The plant emergence is still in the early stages (0-5%) which indicates the safe window to spray herbicides is getting shorty and it is getting riskier as more buds and leaves are formed in sprout fields.


Crop fields:

Please refer to Table 1 for regional F2 % predictions.

In the last few days, many areas in NS experienced a 12-24 wet period which created potentially favorable conditions for apothecia* to re-active and produce disease spores. Under 10 °C conditions, those structures only need about 6 hours to get activated and produce spores. Today’s conditions seemed to be favorable and potential infection risk is expected in crop fields with a high percentage of opening fruit buds.


*Apotheica is a small cup-shaped and spore-bearing structure that is produced by overwintering mummy berries on the ground. 


If you didn’t get a chance to spray crop fields with fungicide before this wet period, you can still put something on after the fields are dry. Most of Monilinia Blight products would have around 48-72 hours back action depending on what you use. If you can spray successfully in this time frame, the risk of getting a blight infection will be lower.


Air temperature and wetness duration are two critical factors in determining the severity of Monilinia infection periods. Please refer to the below figure and your local weather conditions to decide if a fungicide application is needed and when will you need to spray.


Figure 2. Severity Rating of Monilinia Infection Periods

Table 1. Percentage of Wild Blueberry Floral Bud F2 stage

 light green (0-20% F2)dark green (20-30% F2)yellow (30-40% F2) and red (40-100% F2)


Wild blueberry production regions, NS

The average percentage of floral buds at F2



South West Nova Scotia


Queens County

>40%- April 24



Hants County

>40%- April 29



Cumberland County


West Advocate

>40%- April 29


>40%- April 29

Halfway River

>40%- April 29



Colchester County



68% F2- May 10

Murray Siding

88% F2- May 10


40% F2- May 10



Halifax Regional Municipality

>40%- May 8



Guysborough County

30% F2- May 10



Pictou and Antigonish County


Blue Mt. (NSW017)

54% F2- May 10

Moose River (NSW061)

41% F2- May 10



Cape Breton

10-15% F2- May 10