Mummy Berry 2020 - Post #1

Tuesday, April 28, 2020

A few new changes you will notice...I have 2 new blogs, one of which is a blog dedicated to Highbush Monilinia blight monitoring (this one) and another general Berry Blog.  The other big change is the addition of Dr. Sajid Rehman to the Perennia team.  Sajid will be contributing regularly to this blog and many other Perennia publications.

For detailed information please check out Perennia's Management of Mummy Berry Disease in Highbush Blueberry.  A quick reminder that primary infection of mummy berry disease in highbush blueberry requires three conditions to be met:

  1. Inoculum present: history of monilinia blight.
  2. A susceptible host: vegetative buds have 5mm (V2 stage) of green tissue exposed and bud    scales have separated (F2 stage) in the flower buds.
  3. Ideal environmental conditions: wet periods with relatively warm temperatures.
Sajid was in the field Monday morning and observed the following in an early block of Duke:
  1. Mummy berries have started germination but there is no risk of infection yet as most of them are dry/dormant.
  2. Some F2 floral buds were observed but had not yet reached 40%.
  3. Weather has not been conducive to infection but with warm weather towards the end of the week/ weekend, things may move along, so we will recheck on Friday.
Floral bud development late April Annapolis Valley, NS
Development of stipe from pseudosclerotium.

Please keep in mind that regular monitoring is conducted on one farm in the Annapolis Valley, and recommendations will be based on weather data collected in Kings County, Nova Scotia.  It should be fairly accurate for other growers in Kings County but will be a guide only for growers to the west, south, and east. Westerly and southerly locations are generally a little ahead of the Valley while more easterly locations become progressively later.  Therefore, it is important that each grower checks their blocks to determine if their fields are susceptible to infection.

To do this, walk individual variety blocks in a "W" pattern and collect 30 stems randomly along that pattern.  Count the total number of floral buds and then the number that are F2 (5 mm of green tissue is exposed in vegetative buds and when bud scales are separating in flower buds) or beyond.

Divide # F2 buds by the total buds, and multiply by 100 = % of F2

Correct timing of the first spray is critically important for good control. Treatments should not be considered until greater than 40% of the buds are past the F2/V2 stage and there is no need to spray if you have no history of mummy berry disease on your farm. 

If you are below 40% it is too early to spray!

You should expect the next blog post on Friday or Saturday of this week.