Brown rot is a blossom-infecting fungal disease. Infected flowers wilt and die. The brown blossoms remain attached to the twigs, becoming covered with a grayish-brown fungal growth during wet weather. Blossom or fruit infections may spread to twigs. Infected twigs develop sunken, elongate cankers with gumming at the margins. Leaves on girdled shoots turn brown and remain attached. Infected fruit initially show a small brown spot which rapidly enlarges. The fruit remains fairly firm and often becomes covered with gray-brown fungus. Fruit may dry and harden into mummies, which serve as a source of infection in the spring.

Management Options

Non-Chemical Management

Remove mummified fruit in the tree or under the tree to reduce spread of disease.
Prune out infected twigs in late spring or summer. Do not wait until the dormant season, when infected twigs are difficult to distinguish.
Space plantings and prune to provide good air circulation. This will reduce moist conditions which favor disease development.
Avoid overhead watering.
Control insects that cause wounds and provide infection sites for the fungus.
Avoid wounding fruit during harvest.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Apply fungicides just before blossoms open. Make additional applications at full bloom, and when most or all of the blossom petals have fallen. Do not use sulfur products during bloom west of the Cascades. Do not apply copper fungicides after full bloom. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

Bonide Fung-onil Multi-Purpose Fungicide Conc
Active ingredient: chlorothalonil | EPA reg no: 60063-9-4
Bonide Infuse Systemic Disease Control
Active ingredient: propiconazole | EPA reg no: 100-773-4
Bonide Sulfur Plant Fungicide Micronized Spray or Dust RTU [Organic]
Active ingredient: sulfur | EPA reg no: 4-62
Hi-Yield Snake Eyes Dusting Wettable Sulfur
Active ingredient: sulfur | EPA reg no: 7401-188-34911
Lilly Miller Sulfur Dust Fungicide/Insecticide Dust or Spray
Active ingredient: sulfur | EPA reg no: 802-16
Ortho Max Garden Disease Control Conc
Active ingredient: chlorothalonil | EPA reg no: 239-2522
Spectracide IMMUNOX Multi-Purpose Fungicide Spray Conc
Active ingredient: myclobutanil | EPA reg no: 9688-123-8845
This list may not include all products registered for this use.

Images

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Caption: Brown rot blossom infection Photo by: R.S. Byther
Caption: Dead blossoms and gumming from brown rot infection Photo by: R.S. Byther
Caption: Flagging symptoms from brown rot infections Photo by: R.S. Byther
Caption: Brown rot infected fruit Photo by: R.S. Byther

WSU Extension

Hortsense