Highlights
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We measured seasonal changes in ice nucleation activity (INA) of blueberry stems.
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The seasonal changes in stem INA were simulated by cold or freezing treatments.
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Stem INA observed before the first autumnal frost is the highest of biological origin.
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The high INA gradually decreased as the stem underwent recurrent frosts in the field.
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Our revised INA assay was useful for determining INA of small plant samples.