The most common cause of drupelets becoming white is solar injury (sunscald) caused by ultraviolet radiation. Varieties vary in their susceptibility to this disorder. ‘Heritage’ raspberry is susceptible to sunscald.
Scientists have proposed other causes for white drupelets in raspberries, such as tarnished plant bug feeding or powdery mildew infection.
A certain mite feeding on blackberry drupelets causes them to discolor. The cause of white drupelets in blackberries is still unknown.
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