Mummy Berry - Post #9 (Shoot and flower cluster blight)

Wednesday, June 10, 2020

We want to share an important update regarding our High bush Monilinia monitoring. As we mentioned in our last blog post, all the mummy berries have dried up and cannot release ascospores. What we see now, are the symptoms of ascospores damage which were released earlier in the season.

In early maturity varieties, shoot blight symptoms such as drooping of affected shoots, followed by brownish purple discoloration of the upper sides of the midribs and lateral veins of affected leaves and flower cluster blight can be observed (Figure 1 and 2). The tufts of grayish conidia appear along the petioles, midribs of affected leaves, and on the infected peduncle or flower pedicels. These conidia that are forming on the diseased leaf shoots and flower clusters will now be spread further by bees, flies, and wind to open flowers where they will grow down the flower style and eventually form a mummy berry. 

Figure 1. Twig and flower blight. 

Figure 2. Twig and flower cluster blight.

  • Most of mid and late maturity varieties are clean but a regular scouting of the fields is highly recommended to help plan for next years mummy berry management.
  • Usually, fungicide sprays targeted to prevent these flower infections are not cost effective but can be practiced. The pruning of branches is not recommended but the easiest way to prevent further conidial spread would be to simply pick off diseased leaf shoots and flower clusters and drop them to the ground or collect them in a bag. This would limit the spread of conidia that are present now.