Meaning of double blossom

dou'ble blos'som

Pronunciation: [key]
— Plant Pathol. Plant Pathol.
  1. a disease of blackberries and dewberries, characterized by witches'-brooms and flower malformations, caused by a fungus, Cercosporella rubi.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.