Why is budbreak through bloom important in an IPM program?



beginning to bloom

Beginning to bloom.

early bloom, five to ten percent

Early bloom.



full bloom

Flower cluster at full bloom

Budbreak/bloom extends from budbreak to petal fall. Activities for this season generally occur mid-March to mid-April, but dates vary according to region, variety, and weather. Some of the key pistachio pests invade the orchard or are present in the trees during bloom, and therefore, this is a time to:

Use the photos and descriptions to familiarize yourself with the various bloom stages. Visually scan the orchard to estimate.

10% bloom

At 10% bloom, approximately 1 out of every 10 blossom buds is open. To check for this stage, look at a series of tree branches throughout your orchard. At 10% bloom an average of 1 blossom is open for every 9 closed ones on a branch.

Full bloom

Full bloom refers to the point at which the majority of flowers in the orchard are fully open; 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. During 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%.

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