2023 Updates and Seasonal Outlook for NS_ 6th Blight Line Post_ May 9

Tuesday, May 9, 2023

The warm weather we had over the last few days certainly advanced plant development. We didn’t really have windows for pre-emergence herbicide application in Mainland fields and other late fields (Antigonish and Cape Breton) have windows this week to get it done (before 200 GDD).

Most of the mainland fields are in a susceptible period to monilinia blight (Figure 1), so please continue to monitor incoming weather for this and next week. Other fields are also fast approaching 40%. It is looking like by the end of this weekend and early next week, all Nova Scotian fields will be under the susceptible period in terms of crop stages.  


Figure 1. Wild blueberry susceptible stages to monilinia blight infection


Growing Degree Days (GDD) Summary and Plant Development Updates


Figure 2. GDD Summary, May 9, 2023


Here is a summary of the most up-to-date GDD from 13 weather stations in wild blueberry fields. If we look at the average GDD, we are around 200 GDD which is a threshold and safe point to apply pre-emergence herbicides.

Please refer to my last blog post for information on sprout and crop fields management recommendations: http://www.novascotiawildblueberryblog.com/2023/05/2023-updates-and-seasonal-outlook-for_5.html


Nova Scotia (Kentville station) Soil Temperature Update

Here is another update on the soil temperatures contributed by Jeff Franklin (AAFC- Kentville).

Figure 3. Soil temperature update- May 8

It is looking like soil temperature might be on the rise after May 9, which can contribute to faster plant development and that’s what we learned in 2022. If this trend continues, we might see an early bloom year. Blueberry growers and beekeepers should watch for that and be prepared. However, things can change so I will continue to update this information as I receive them. Right now, it is too early to make a clear statement about this.


Wild Blueberry Floral Bud F2 Stage

Please see the below summary table of the percentage of wild blueberry floral bud at the F2 stage. You can also click on this map to check those numbers. Detailed information is also available under the Wild Blueberry Blog- GDD& Phenology Tracker.

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



Cape Breton

15% F2- May 9



Antigonish County

20% F2- May 9



Pictou County

25% F2- May 9



Guysborough County

35% F2- May 9



HRM (Dean, Musquodoboit…)

>40% F2, watch the weather forecast and prepare for spraying



Colchester County

>40% F2, watch the weather forecast and prepare for spraying



Cumberland County

>40% F2, watch the weather forecast and prepare for spraying



Hants County

>40% F2, watch the weather forecast and prepare for spraying



South West Nova Scotia

>40% F2, watch the weather forecast and prepare for spraying