Brown rot causes blossom blight, twig blight; twig canker and fruit rot.[3] Brown rot is caused by a fungus that produces spores, and can be a major problem during particularly wet seasons. Prolonged wet weather during bloom may result in extensive blossom infection. The length of wet periods required for blossom infection depends upon the temperature. Humid wet conditions are when the fruit trees are most at risk from infection. Young green fruit can be infected just before autumn, but the infection often remains inactive until near maturity of the fruit. Brown rot can spread after harvest. Mature fruit can decay in only 2 days under warm conditions.[3]
Blossom Blight: Infected blossoms wilt, shrivel and become covered with greyish mould. Petals may appear light brown or water-soaked. Blighted blossoms do not produce fruit. Dead blossoms may stick to spurs and twigs until harvest, providing a source of spores for the fruit rot phase.[3]
Twig Blight and Canker: On peaches and apricots the infection may spread to twigs, causing brownish, oval cankers that may girdle and kill twigs.[3]