Mummy Berry 2019 #2

For the primary infection of monilinia to occur you need three things:

1.       Inoculum present: history of monilinia blight.
2.        A susceptible host: vegetative buds have 5mm 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.

With that in mind it appears that we had our first infection period this past Saturday April 27, 2019.

Observations made Saturday April 27, 2019 from a blueberry field in the Annapolis Valley showed that mature apothecia cups are present (requirement #1), and buds are at the F2 stage (requirement #2). From weather data collected in the Annapolis Valley on Saturday April 27, 2019 there were 15 hours of leaf wetness, and an average temperatures of 7 degrees Celsius (requirement #3). Since all three requirements for infection were met, there was most like an infection period on Saturday April 27, 2019. 

Bud stage from April 29, 2019

Apothecia cup from April 29, 2019

If you did not apply a protective spray before the infection period, you can still achieve control of infections that have already occurred by application of a fungicide with back-action capability (Topas, Mission, etc) within 72 hours of the beginning of the event. For more information on sprays and monilinia please refer to Management of Mummy Berry Disease in Highbush Blueberry.

As a reminder though these recommendations are based off of conditions observed in the Annapolis Valley, Nova Scotia and may not be applicable to your location. Infection periods only occur when bud development has reached the F2 stage, monilinia spore cups are present, and temperature and moisture levels are ideal. The decision to spray should be based on these conditions being observed in your particular field.