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Why Is the Bloom Season Important in an IPM Program?

Bloom season, which extends from the green tip stage to petal fall, is a key time to control many diseases. Many of the key pests are present and there is not a lot of foliage, so good spray coverage is easier to achieve than later in the season.

Time some actions based on an estimate of when a certain proportion of the flower buds are fully open; for example, 5% bloom and 10% bloom are estimates of when the first 5% or 10% of flower buds have reached the full bloom stage. For pest management, the term “full bloom” refers to the point at which the majority of flowers are fully open; by this time some will be past full bloom, while others will be at earlier stages. The proportion of flowers that are fully open when the orchard is at full bloom can vary substantially depending on winter chilling. In high-chilling years, as many as 80% of the blossoms may reach full bloom at the same time. In low chilling years, the proportion may be below 50%.

Bloom stages
Green tip stage of peach bloom.
Green tip
First pink stage of peach bloom.
First pink
Green tip stage of plum bloom.
Popcorn (Pink bud)
Full bloom stage of peach.
Full bloom
Petal fall stage of peach.
Petal fall
Jacket stage of peach.
Jacket split

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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