4.29.15 Mummy Berry Season 2015 is Here

Knox, Lincoln and Waldo Counties

I  have reports from West Rockport, Liberty, and Appleton that numerous mummy berry pinheads (the precursors to apothecia) and a few mature mummy berry cups (apothecia) capable of producing spores are present.  These will continue to develop with the rain we have been getting and I expect we will have lots of mature cups by the end of the week.

The plants are not as far developed.  Reports and what I have seen, it looks like we are getting quite a few F2 (crown stage) flower buds but are not at 40% at the crown stage yet.   Please look at your plants and count your flower buds (see below) to see what stage your plants are.

Hancock and Washington Counties

I have reports from Ellsworth, Eastbrook, Jonesboro and throughout the barrens from Columbia to Wesley that pinheads are starting and some very early cups have been see in a few fields too.

Picture of developing flower buds. Flower buds are susceptible to the mummy berry fungus once they have separated enough to look like small crowns.Again the plants are not ready yet in these areas.  I have reports of some F2 flower buds but not yet at 40%. Please look at your plants and count your flower buds (see below) to see what stage your plants are.

When are Plants Susceptible?

Flower and leaf buds are protected from the fungus when they are enclosed in their bud scales.  They need to open up and expose new tissues before they are susceptible.   The best way to determine when you have enough susceptible tissue to apply fungicides is to look at the flower bud development.  Look at a minimum off ten stems (preferably 20 stems)  randomly chosen across your field.  Count the total number of flower buds and the number of flower buds at F2 stage (see picture).  Divide the number of Flower buds at F2 by your total number of flower buds and multiple by 100 which will give you your percent of F2 Flower buds.  You want to count all of your flower buds  since most of the time the buds at the top of the stems are faster than the lower buds and if you just count those you will over estimate how far along your plants are.  When you are at 40% many of the leaf buds will also be showing some green and  will be susceptible.

Timing of Fungicide Applications

Keep in mind you should rotate your fungicides if you make more than one application. Most of the Group 3 fungicides allow only two applications per year due to concerns about resistance developing.

  • Method 1. Protectant method. Apply fungicide as a protectant when you have 40% of your flower buds at F2 stage and then every seven to ten days after until the cups are no longer present.
  • Method 2. Protectant and weather method.  Wait until you have 40% of F2 flower buds AND there is an upcoming weather event that may cause infection, and then apply fungicides.  You will save your fungicide application to when you need it and not waste it on protecting plants when there is no or very low risk of infection occurring.
  • Method 3. Infection period method.  Wait until you have 40% of F2 flower buds AND an infection period has occurred, and then apply fungicides with kickback activity (such as the azole fungicides) within 72 hours of the infection period.  The fungicide application will kill off any fungus that got into your plants and protect them for the next seven to ten days.

If you have a mummy berry plot, I would love to hear from you.  If you have any questions please contact Seanna Annis at sannis@maine.edu or the Blueberry Hotline 800.897.0757 (in Maine).