Cherry Rot

Asked May 20, 2020, 11:04 PM EDT

Large fruit set but 50% or more of clusters have 3 or more yellowing / browning fruits. Some clusters are still free of this.

Multnomah County Oregon

1 Response

Thank you for the image. It reveals that your cherries have a common disease, Brown Rot Blossom Blight and Fruit Rot. This year, the frequent light rains has been especially favorable for this disease among the various Prunus species.

Treatment has two required phases: 1.) Cultural and 2.) Chemical.
1.) Cultural management
a.) Remove all affected fruit, both on the tree and on the ground. Discard in the trash.
b.) Some affected fruits (called mummies) will dry and cling to the tree through the winter. Remove,, and discard, them when you see them because they are a major source of infection spores the following spring.
c.) Prune out dead twigs and branches during dry weather in the summer.

2.) Chemical treatment prescribes an annual spray to minimize recurrence of the disease.
Four products are available to home gardeners. Choose from the following, then read and follow label directions to apply:
- Bonide Captan 50 WP
- Ortho MAX Garden Disease Control
- Infuse Systemic Disease Control
- Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens.

Apply fungicides during the bloom period at early popcorn (red bud, pink bud, or green tip), full bloom, and/or petal fall to control the blossom blight phase.

If the tree is too large for you to easily spray, consider hiring a pest control company.