5th Blight Update and Seasonal Outlook for Nova Scotia- May 6, 2022

Friday, May 6, 2022

Another update before the weekend.

Wild Blueberry Floral Bud F2 Stage and Monilinia Infection Periods

As I mentioned in the last update on Tuesday, May 3, a lot of fields in the central area are at or beyond 40% F2 and by looking at weather stations installed in wild blueberry fields, starting Wednesday evening (May 4) to Thursday morning (May 5), there could be a moderate to high infection period during this time.

It looks like we will have a warmish and dry week next week according to the information from Environment Canada and those stations we have in wild blueberry fields (see Table 2.). You might be able to drag the first monilinia application to a further time before the next wet weather is forecasted.

It is a little bit early to talk about when to stop worrying about monilinia blight infection and treatment application, but I want to put this information out early. This graph shows what are some susceptible stages/periods for spores to infect blueberry buds/leaves.

We do not have a threshold for when we should stop monilinia blight application, but a good way to look at this question is when the crop has reached the stage where the leaves have unrolled or the first blossoms are visible the susceptible period is past and sprays are not required.

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)

*Once the areas and fields get to 40% F2 or above, I will stop updating numbers as I can focus on other areas. Once you are at or above 40%, please monitor your local weather and make a management decision.


Wild blueberry production regions, NS

The average percentage of floral buds at F2



Cape Breton




Cumberland County


Oxford (early field)

May 5- 46%

Mapleton (Lynn Mt.)

May 5- 49%

Halfway River

April 26- 40%

Lower Greenville

April 25- 15%

Westchester Station

April 25- 17%


May 2- 40%


May 3- 41.2%

Diligent River flat

May 5- 10-15%


May 2- 40%

New Canaan

May 5- 40%


May 3- 34.7%

Windham Hill

May 3- 13.8%

Prospect and Newville Rd. area

May 5- 30-35%

York Settlement/ Glasgow Mt.

May 5- 30-35%

Fox Point

May 5- 20%



South West Nova Scotia


Queens County

April 23- 42%

Digby County

April 29- 50%

Annapolis County

April 29- 50%



Hants County




Halifax County




Guysborough County




Colchester County


Murray Siding

May 5- 72%


May 5- 35%


May 5- 49%

Debert (WBPANS office)

May 2- 44%

Debert (Debert Airport)

May 2- 45%

Debert (near the railway track)

May 2- 40%

Baseline Rd.

May 2- above 40%


May 6- 50%


May 2- 40%


May 2- 40%

Highland Village

May 2- 27%

Great Village

May 2- 27%

Tatamagouche Mt.

May 2- 17%



Pictou and Antigonish County


New France

April 27- 5%


April 27- 5%

Mt Thom

April 27- 12%


April 27- 15%

Sunny Brae

April 28- 5%

*Thanks to everyone who contributed information and a special thank you to staff from the Bragg group (Roy Hunter and Richard Langille) who share information with me weekly.


Table 2. Weather Forecast for Potential Wetness and Monilinia Infection Periods

Weather Station and Location

Potential Wetness and Monilinia Infection Periods

*ONLY when your field is at or above 40%!!!

*Predict period: May 7-12; reported date: May 6



Glenholme (NSW001)


Murray Siding (NSW002)


Upper Kemptown (NSW022)


Kavanaugh Mills (NSW023)


Debert (NSW036)


Belmont (NSW037)


Staples Brook (NSW038)






Wyvern (NSW003)


Oxford (NSW005)


Halfway River (NSW039)






Blue Mountain (NSW017)


Sunny Brae (NSW018)


New Gairloch (NSW019)


Keble (NSW020)


Four Mile Brook (NSW021)


College Grant (NSW040)




*Weather source: weather stations in wild blueberry fields (http://www.novascotiawildblueberryblog.com/p/weather.html)


Sprout Field Development and Observation

According to the wild blueberry sprout year GDD development model (Plant emergence starts at 270 GDD), we are not there yet. However, with this warm weather, it is expected to see sprout field plants start emergence by the end of next week. From my observation in sprout fields, I haven’t seen plant emergence occurring yet.

According to a report and observation from the researcher, it was noticed that a lot of shoots sprouting from the base of cut stems and those fields with partially cut stems have formed a lot of buds at the base (see photo below). This would be something for you to watch for if you are going to apply your spring herbicides.

Photo credit: Scott White