Brown Rot Blossom Blight and Fruit Rot

Monilinia fructicola and M

35 host plants · Fungal

Last updated

Brown rot causes blossom blight in spring and fruit rot at harvest on stone fruits. You see blighted flowers and brown, decaying fruit. The disease favors warm, wet conditions. Prune out infected blossoms, maintain good orchard sanitation, and apply fungicides during vulnerable flowering periods.

These must be supplemented by chemical methods especially in the wettest areas such as west of the Cascade Range. Remove and destroy infected twigs and branches in summer.

Quick Reference

Agent Type
fungal
Causal Agent
Monilinia fructicola and M
Host Plants
35
Spread
wind
Favorable Conditions
Warm, wet conditions during bloom; optimum 68-77°F (20-25°C) with free moistu...
Now: Bloom Infection Window (Critical)High Risk

Flowers open and are highly susceptible to infection during wet weather. Infection requires temps above 50°F (above 55°F for M. laxa). Secondary spore production occurs on infected floral tissue.

Next: Fruit Development - Latent Infection Risk

Management

Vulnerability Window

Full bloom period (primary risk window, April-May in Puget Sound). Latent infection risk from bloom through pit hardening (May-June). Declines at embryo growth then increases again as fruit ripen (Aug-Sept). Ripening fruit are highly susceptible near harvest.

What Triggers Infection

Warm, wet conditions during bloom; optimum 68-77°F (20-25°C) with free moisture (rain, irrigation, dew). Conidia germinate readily on wet flower tissue. Infection requires free water or high humidity. M. fructicola: infection above 50°F. M. laxa: infection above 55°F. Cold springs delay apothecial development; warm, wet springs accelerate disease. (Source: PNW Plant Disease Management Handbook)

Cultural Controls

  • Cultural controls should be supplemented by chemical methods in areas with extended spring moisture.
  • Remove and destroy infected twigs and branches in summer.
  • Shorten large trees and prune out shaded limbs in summer for a more open canopy that dries out quickly.
  • Remove and destroy all mummified fruit in and around the tree.
  • Cultivating or burying old fruit before the growing season will not reduce the risk of this disease.
  • However, removing fallen fruit (due to thinning or lack of pollination) can significantly reduce the amount of rot at harvest.
Regional Notes

In maritime western Washington (west of the Cascades), do not use sulfur products during bloom. Chemical controls are especially critical in these high-rainfall areas where extended spring moisture prolongs infection periods.

Host Plants (35)

Betula lenta Sweet Birch, Cherry Birch, Black Birch Malus robusta Cherry, Crabapple Prunus americana Wild Plum American (Red) Plum August Plum, Goose Plum Prunus avium Sweet Cherry Prunus besseyi Sand Cherry, Western Sand Cherry Prunus blireiana Blireiana Plum Prunus caroliniana Carolina Cherrylaurel American Cherrylaurel Prunus cascade Prunus cascade Prunus cerasifera Cherry, Plum Prunus cistena Purpleleaf Sandcherry Redleaf Sandcherry Cistena Sandcherry Cistena Plum Prunus dream Prunus dream Prunus emarginata Bitter Cherry, Wild Cherry, Quinine Cherry Prunus first Prunus first Prunus fruticosa Steppe Cherry, European Dwarf Ground Cherry, Mongolian Cherry Prunus glandulosa Dwarf Flowering Almond Prunus ilicifolia Hollyleaf Cherry, Holly-leaved Cherry Prunus lusitanica Portugal Laurel Prunus maackii Amur Chokecherry Amur Cherry, Manchurian Cherry Prunus mume Japanese Flowering Apricot Prunus newport Newport Flowering Plum Prunus okame Okame Flowering Cherry Prunus padus European Birdcherry Common Birdcherry Prunus prostrata Rock Cherry, Mountain Cherry Prunus sargentii Sargent Cherry, Sargent's Cherry Prunus serotina Black Cherry, Rum Cherry Prunus serrula Birchbark Cherry, Paperbark Cherry, Tibetan Cherry Prunus serrulata Japanese Flowering Cherry Prunus snow Prunus snow Prunus subcordata Klamath Plum, Sierra Plum, Pacific Plum Prunus subhirtella Higan Cherry Prunus subhirtella var. autumnalis Autumn Flowering Higan Cherry Prunus tai Prunus tai Prunus virginiana Prunus virginiana Prunus virginiana var. demissa Western Chokecherry Prunus virginiana var. virginiana Common Chokecherry, Eastern Chokecherry

Sources & References

Primary: PNW Plant Disease Management Handbook

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