Mummy Berry - Post #8 (infection period ended)

It was a bit of a weird start to the season, with a lot of cool temperatures, resulting in a slow progression in both the development of highbush blueberries and apothecia cups that result in infection of monilinia blight (mummy berry).  Farms should have put on 2-3 protectant sprays that would have protected the plants for the length of the infection period.

Most, if not all varieties should now be at or beyond F2 (Figure 1 and 2), and with the most recent stretch of dry conditions (25 May, 2020) there should be limited risk of monilinia blight infection periods.

Sajid is reporting from his monitoring that apothecia cups (the fruiting bodies that produce the infection spores) have dried up, eliminating the risk for infection (Figure 3).

 Figure 1. Floral bud development in early maturity variety.

Figure 2. Floral bud development in late maturity variety.

Figure 3. Dried apothecial cups of mummy berry. 

Stay tuned to the Berry Blog as we continue to monitor plant and pest development throughout the season. 

Mummy Berry 2020 - Post # 7

Over the past weekend we expected major progress in floral bud development. As you can see in Figure 1, temperatures from March 01 to May 19, 2020 are still tracking significantly behind the 5- and 10-year averages.

Figure 1. Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1st to May 19th for the past 17 seasons. Provided by Jeff Franklin (AAFC).

On Tuesday May 19th, Sajid confirmed that the early block of Duke he is monitoring now has 85-95% of floral buds are at F2 (bud scales have separated in the flower buds), as shown in Figure 2. Furthermore, the medium maturity variety has 60-70% of the floral buds at F2 stage (Figure 3). However, in the block of late variety, 35-50% buds are susceptible to Monilinia blight infection (Figure 4). 

Almost all apothecial cups have been matured (Figure 5) and they are drying up. If you already had sprayed once with the propiconazole, there is no need of additional spray at this point as the weather will be dry with no rain forecast for the next one week. If you have not sprayed in the last 7-10 days, it would be a good idea to apply a protectant spay to get you through. Please keep in mind that the propiconazoles (e.g. Pivot, Bumper, Tilt, Mission, Fitness, and Propi Super) with back action can only be sprayed a total of 2 times per season, so plan your sprays appropriately.

Figure 2. Early maturity variety, floral buds at F2 stage of development.

 Figure 3. Mid maturity variety, floral buds at F2 stage of development.

 Figure 4. Late maturity variety, floral buds at F2 stage of development.

Figure 5. Mature apothecial cups. 

To determine whether a planting has buds that have reached 40-50% F2, follow this protocol for floral bud evaluation:

In a field, block or variety (whatever area you would spray at one time) walk a zig zag (not only the edge) stopping a total of 5-10 times to count floral buds.  With each stop, count 10-15 floral buds on a stem and use that to guesstimate the floral bud stage on that plant.  Use your 5-10 plant guesstimates to determine the average floral bud stage of the field, block or variety.  Remember, you want to protect any planting that has 40% or higher of floral buds at F2 (Figure 1 above).

As a reminder, these recommendations are based on conditions observed in the Annapolis Valley, Nova Scotia and may not be applicable to your location. The decision to treat should be based on appropriate conditions observed on your farm and in particular fields/blocks. For detailed information please check out Perennia's Management of Mummy Berry Disease in Highbush Blueberry. 

A complete list of registered products can be found in Perennia's Highbush Blueberry Disease and Insect Management Guide.

Mummy Berry Infection Alert!

This update is to report that there was a precipitation event on Monday evening and night that was a high risk for mummy berry infection!  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 protect your fields from the infection by application of a fungicide with back-action capability within 72 hours of the beginning of the event.  The beginning of the wetting period at the site on Brooklyn Street here in Kings County was recorded at 8 p.m. so growers in this area of Kings County would have until 8 p.m. on Thursday May 5^thto apply a control for back-action protection.

The weather forecast for Kings County is calling for 20-30 mm of rainfall Wednesday night and Thursday so a spray for back action control should be made today while an application window is available.  This spray will protect against the infection period Monday night as well as the one forecast for tonight and tomorrow.

Mummy Berry Forecast - April 29, 2016

Once again, primary infection for mummy berry disease in highbush blueberry requires three conditions to be met:

1. Inoculum presence - mature sporulating apothecia cups,
2. Susceptible bud development stage – bud scales separating in flower buds (F2 stage), and
3. Suitable weather conditions – long wet periods at relatively warm temperatures.

Also, it is not recommended to spray until 40-50% of buds of a given variety are at the F2 stage and there is no need to spray if you have no history of mummy berry disease on your farm.

Observations as of Thursday April 28^st:

• Mature apothecia cups are now present and actively sporulating so we have inoculum present at this time.

• The early variety ‘Bluetta’ had 70% of flower buds at the F2 development stage while the mid-season variety ‘Bluecrop’ was found to have 50% of its flower buds at the F2 stage. The late mid-season variety ‘Nelson’ was at 10% F2 while the late varieties ‘Jersey’ and ‘Burlington’ were at 0% F2. Surprisingly, the early variety ‘Duke’ was only found to be at 10% F2 but it appears most early and mid-season varieties are now at the ideal development stage for infection.

• A 15.5 hr long wet period from Saturday afternoon April 23^rd through to early Sunday morning April 24^th would have been sufficient for a high risk infection period but most (if not all) varieties would not have been at a susceptible bud stage and very little (if any) active spores were present at that time in Kings County; however, we can now say that we are now in the primary ‘mummy berry infection season’ and must either use a “fixed sprayed schedule” to protect bushes from infection or a ‘weather based spray program’ to control infections using controls that have “back-action” capability (eg. Topas).

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. As such, most early and mid-season varieties would benefit from their first cover as soon as possiblewhile sprays to later season varieties may be delayed until their bud-development reaches the recommended 40-50% F2 stage.

 

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 Funginex, Mission, or Topas. An additional spray(s) may be required, depending on weather conditions, 7-10 days later. Identification of infection periods for back-action control will be communicated through this forecast in the coming weeks so please stay tuned and have your sprayers ready.

 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. Once again, if you are to the south and/or west of Tim’s location in 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.

 

Latest Mummy Berry Forecast

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 – bud scales separating in flower buds (F2 stage), and
3. Suitable weather conditions – long wet periods at relatively warm temperatures.

Also, it is not recommended to spray until 40-50% of buds of a given variety are at 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”.

                                                 Flower buds at F2 (bud scales separating)

Observations on Thursday April 21^st:

• Apothecia cups at the “pinhead” stage of development were found but were not actively sporulating and as such there is no inoculum at this time.
• Flower buds are not yet at the 40-50% F2 development stage recommended for spray application.The early variety ‘Bluetta’ had 15% of flower buds at the F2 development stage while Duke, Bluecrop, Nelson, Jersey, and Burlington had 0-4% flower buds at the F2 development stage.
• Showers and light rain is forecast for Saturday April 23^rdand Tuesday April 26^th.

Recommendations:

It is still too early to spray as of April 22^nd (at Tim’s farm), but we are getting close! There are immature apothecia cups present and buds of some early varieties are approaching the 40-50% F2 stage recommended for first spray. Suitable weather conditions for infection (long wet periods and mild temperatures) are possible within the coming week but most varieties will not be advanced enough to warrant protection. 

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. Once again, if you are to the south and/or west of Tim’s location in 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. 

First Mummy Berry Forecast of 2016

Perennia will be delivering a mummy berry disease forecast for highbush blueberries again in 2016. 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”:

http://www.perennia.ca/Fact%20Sheets/Horticulture/Fruit/Highbush%20Blueberry/Management%20of%20Mummy%20Berry%20Disease%20in%20Highbush%20Blueberry.pdf 

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. As of yet, we do nothave buds at the susceptible development stage and 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. As such growers should have their sprayers ready to go.

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 found at http://www.perennia.ca/Pest%20Management%20Guides/Fruits/2016/Highbush_I&DGuide_2016.pdf