How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Brown rot

The fungus that causes brown rot survives the winter in infected twigs, inside dead, blighted blossoms that remain on the tree, or in dried, rotted fruit on the tree or on the ground. Spores produced on these sites in spring are carried through the air by wind and splashing water to infect flowers of the new year's crop.

Brown rot infection and disease development will take place over a wide temperature range and flowers can be infected from the time buds open until petals fall. Water must be present on the flower surface for infection to occur. Little or no blossom blight develops if there is no rain during the bloom period and irrigation does not wet flowers. Fruit is most susceptible to infection by the brown rot fungus when it is ripe. Most fruit rot develops during the month before harvest, although rot occasionally may develop on green fruit in early summer.

Brown rot overwinters on twigs in cankers
Brown rot overwinters on twigs in cankers
Infected blossoms
Infected blossoms
Knotted fruit
Knotted fruit

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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