Brown Rot

    Brown Rot

    Early stage brown rot. Early stage brown rot.

    Brown rot shriveled fruit.
    Brown rot shriveled fruit.

    HOSTS

    • Cherry
    • Peach/nectarine
    • Plum

    DESCRIPTION

    Brown rot is a disease of warm, humid environments and requires several hours of rainfall to spread and cause infections. The two most susceptible periods for fruit infection are the blossom stage through peach pit hardening, and the two to four week period before harvest.

    BIOLOGY

    The brown rot pathogen overwinters on previously infected fruit, called "fruit mummies". Spores are blown by wind and rain to infect flowers on ripening fruit.

    The pathogen can enter fruit when any type of injury caused by insect damage, hail/heavy rain injury, bird pecks, bruising, or cracking, is present.

    On ripening fruit, symptoms first appear as a small tan spot that quickly enlarges (within 2 to 5 days) until the whole fruit rots. If conditions remain moist, a mass of light grey-brown spores will form on the fruit surface. Fruit that is left on the tree will shrivel and dry out. This mummified fruit will carry spores over the winter, increasing the risk of blossom infection the following spring.

    SYMPTOMS

    • Mass of light grey-brown spores on fruit surface
    • Shriveled, wrinkled fruit

    GENERAL MANAGEMENT

    Remove all infected fruit from the trees and ground. Mowing over them can help to prevent overwintering survival. Fungicides can help to control brown rot, but should only be used when the pathogen has been identified. (Other rots can look similar) Where brown rot is a problem, fungicides should be used after petal fall and close to harvest if the weather is cool and rainy during those times.


    Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.