Mummy Berry Forecast 2017 #6

All areas of mainland Nova Scotia are well past the 40% F2 stage.  In our scouting activity in Kings County this week we did not find any cups. Hopefully that means much, if not all, of Nova Scotia is out of the infection period.

Realizing it is May in Nova Scotia, the forecast looks quite good until Monday the 22nd. If this weather pattern holds, any remaining apothecia cups in later areas of the province should dry up.

Please scout your own fields for bud stage and apothecia cups.

Mummy Berry Forecast 2017 - #5

During the break in weather today I got out to check for the presence of mummy berry inoculum.  There are still apothecia cups shooting spores and thus, a risk for infection.  

Since the beginning of May we have had several infection periods depending on where in Nova Scotia you are located.

- Last Monday and Tuesday was a long infection period for most of the province. 
- Friday evening through early Sunday morning was an extended infection period for most areas as well. 
- Finally, this past Tuesday afternoon into Wednesday was also an infection period.

There looks to be a break in wet conditions this weekend, forecasting sunny conditions for Friday through to Sunday.

If fields have not be treated in the last 4-5 days and they are above the 40% F2 stage a treatment should be considered. Highbush Blueberry Management Schedule.  

Most fields being monitored in Kings County, Nova Scotia are at or above the 40% F2 stage and if mummy berries are in the field, they will be actively sporulating.

Mummy Berry Forecast 2017 - #4

This update is to report that with the extended precipitation over the last few days, along with sporulating apothecia cups there was a risk for mummy berry infection!  Although temperatures were low on Monday, the wetness duration was long with precipitation starting at noon on Monday May 1st.  Temperatures reached the teens yesterday, May 2nd in Kings County.  If you had a spray on within a week to 10 days before this event you were likely protected.  If you did not, you can still control infections that have already occurred by application of a fungicide with back-action capability (Topas, Mission) within 72 hours of the beginning of the event. 

Monilinia blight infection risk model.

The weather forecast for Kings County is calling for rain Friday night through to Monday so a spray should be made while an application window is available. Applying a spray with back action will control infections that occurred this past Monday and Tuesday and will protect against infections that are likely going to occur on the coming weekend. Please check your regional forecast to determine the best time for a spray application.

For a complete list of products available for monilinia blight (mummy berry) control in highbush blueberry please see the Highbush Blueberry Management Schedule.

Just a reminder, the decision to spray for Monilinia blight (mummy berry) depends almost entirely on the past history of blight in a particular field.  If growers have experienced a problem with blight in the past, they should apply controls.  If you do have a history of Monilinia infection, applications do not need to be made until greater than 40% of the fruit buds have reached the F2 stage.  

All growers should be monitoring their fields closely, looking at floral and vegetative bud development.  More information on mummy berry can be found in Perennia's Management of Mummy Berry document.

Finally, please remember that the observations and recommendations above are derived from data collected in Kings County, Nova Scotia and may not be applicable to your location. If you are to the south and/or west of Kings County you may well be ahead in development and if you are located to the east of the Valley you will generally be later. This forecast is to be used a guide only for mummy berry disease management in Nova Scotia. 

Mummy Berry Forecast 2017 - #3

With these in mind, our observations from today, 28 April 2017:

Today on my scouting, I was joined by Dr. Paul Hildebrand in the hunt for apothecia cups. It is like looking for a needle in a hay stack but we did find mature apothecia cups that are actively sporulating, so we have inoculum present at this time.

Can you find the apothecia cups?
Like I said, a needle in a hay stack!

Mature apothecia cups in moss
under a highbush blueberry bush.

The weather the last few days in the Valley and across much of the province has been conducive to the both the development of the apothecia cups and the crop.

Depending on variety and location, highbush blueberry development varied.  I strongly encourage growers to check their fields and varieties for stage of growth to determine the need to spray.  During our scouting today we did observe 'Bluecrop' with over 40% of the flower buds at F2, while late season variety 'Elliot' had less than 40% at the F2 stage.

Recommendations:

A ‘fixed spray schedule’ may be used to manage the disease whereby the first fungicide spray should be applied when 40-50% of the flower buds have reached the F2 stage (flower bud scales separating). One or more additional sprays may be required on a 7-10 day schedule. 

Alternatively, a ‘weather based spray schedule’ may be employed. This strategy uses temperature and leaf wetness duration to determine if an infection period has occurred. If an infection period occurs and mature apothecia are present, and flower buds have reached the 40-50% F2, then the grower has up to 72 hours after the start of the wet period to apply registered fungicides with back-action. These include Topas, Mission, and Funginex, although the latter cannot be applied if berries are to be exported to the US. Additional spray(s) may be required, depending on weather conditions, 7-10 days later. 

Finally, please remember that the observations and recommendations above are derived from data collected in Kings County, Nova Scotia and may not be applicable to your location. If you are to the south and/or west of Kings County you may well be ahead in development and if you are located to the east of the Valley you will generally be later. This forecast is to be used as a guide only for mummy berry disease management in Nova Scotia.

Mummy Berry Forecast 2017 - #2

A quick reminder that primary infection of mummy berry disease in highbush blueberry requires three conditions to be met:

1. Inoculum presence – mature sporulating apothecia cups;
2. Susceptible bud development stage – vegetative buds have 5 mm of green tissue exposed and flower bud scales are separating (F2 stage);
3. Suitable weather conditions – long wet periods at relatively warm temperatures.

On Tuesday April 25 we found a few dried up initials but no apothecia cups, and as such no inoculum at this time.  However, if we get rain, initials will likely continue to grow, or new ones will emerge.

Flower buds at F2 (bud scales separating)

There is a report from South West Nova Scotia that some varieties are at the 40% F2 stage. I have no reported fields in Central Nova Scotia that are at the 40% F2 stage. However, with the forecast of warm weather for the next several days, growers should begin monitoring their fields to determine the level of bud development.  Bud development differs greatly from one area to another, so growers must take the time to inspect their own fields and have the fields sprayed at the proper time.

Correct timing of the first spray is critically important for good control. Treatments should not be considered until greater than 40% of the fruit buds are past the F2 stage and there is no need to spray if you have no history of mummy berry disease on your farm. For more information and pictures refer to “Management of Mummy Berry in Highbush Blueberry”.

Table 1. Wetting duration (in hours) associated with mummy berry infection at different air temperatures in Nova Scotia, Canada (Data from Paul Hildebrand and Rick Delbridge).

Note that several fungicides registered for mummy berry disease (eg. Topas) have what is referred to as “back-action” activity and can effectively control an infection if applied within 72 hours of the beginning of the infection period. For a complete list of registered products please refer to “Highbush Blueberry Insect and DiseaseManagement Schedule”.

Finally, please remember that the observations and recommendations above are derived from data collected in Kings County, Nova Scotia and may not be applicable to your location. If you are to the south and/or west of Kings County you may well be ahead in development and if you are located to the east of the Valley you will generally be later. This forecast is to be used a guide only for mummy berry disease management in Nova Scotia. 

Look for the next update late in the afternoon on Friday, April 28th.

Mummy Berry Forecast 2017 - #1

It is that time of year again and Perennia will be delivering a mummy berry disease forecast for highbush blueberries again in 2017.  Please keep in mind that Tim Strong is our co-operator on this project and recommendations will be based on weather data collected on his farm on Brooklyn Street, Kings County, Nova Scotia. It should be fairly accurate for other growers in Kings County but will be a guide only for growers west, south, and east of his location. Westerly and southerly locations are generally a little ahead of the Valley while more easterly locations become progressively later.

To review the disease, its symptoms, and life cycle, please examine the fact sheet on Perennia’s website titled “Management of Mummy Berry Disease in Highbush Blueberry”.

The important thing to remember about the disease is that you need three things for infection to occur – inoculum, susceptible bud development stage, and suitable weather conditions.

During scouting yesterday, a few varieties had buds that were just beginning to separate but for the most part, we do not have buds at the susceptible development stage.  No apothecia cups (for inoculum) have been found. However, buds are expanding on early varieties and if mild conditions persist we could well be at susceptible development stages for some varieties over the next week.  Have you sprayers ready!

Blue Gold at F1.

Scouting 20 April, 2017, Kings County.  Spartan at F1.

For a review of the fungicides registered for use on this disease please take a look at Perennia’s Highbush Blueberry Insect and Disease Management Schedule.