Bitter Pit

    Bitter Pit

    Bitter pit lesions. Bitter pit lesions.

    Bitter pit flesh discoloration.
    Bitter pit flesh discolorations.

    HOSTS

    • Apple

    DESCRIPTION

    Bitter pit is a disorder of apple fruit caused by a deficiency of calcium, and symptoms are usually seen after harvest. Granny Smith, Jonathan, and Golden Delicious are a few susceptible varieties. Rome Beauty, Macintosh, Gala, and Fuji are less susceptible. Affected apples will have sunken lesions on the skin, with brown, spongy tissue underneath.

    BIOLOGY

    Bitter pit and late-season stinkbug injury look similar. Bitter pit lesions are usually distributed on the sides and bottom of the apple and are circular in shape. Lesions become worse after storage, turning dark brown to black.

    Stink bug injury is usually located higher on the fruit (near the stem), is conical or rectangular in shape, and turns the flesh light tan to dark brown.

    Bitter pit usually occurs on trees with low fruit set, excessive vigor, irregular soil moisture, or on certain varieties. The varieties listed above are the most susceptible, although almost any young, extremely vigorous tree may exhibit symptoms.

    SYMPTOMS

    • Brown, sunken lesions on the skin
    • Brown, spongy tissue below the skin surface

    GENERAL MANAGEMENT

    • Maintain trees at a moderate level of vigor
    • Do not over-fertilize, as vigorous trees can be more susceptible
    • Maintain even soil moisture
    • Do not over-thin
    • Keep trees at annual bearing
    • Do not excessively prune at dormancy
    • Prune in summer to remove excess growth

    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.