Botrytis rot of blueberries

Botrytis rot (grey mold) is a fungus that grows at temperatures as low as 32°F, but growth is slow at this temperature. Following wet weather during mid to late bloom, individual blossoms or entire fruiting clusters will wither and die. The disease is not a problem during the summer months but can cause rotting of harvested fruit. It is believed that Botrytis blight is less of a problem where burning is used for pruning, and the disease can be managed with properly timed fungicide applications.

Botrytis blossom blight is an important disease of blueberries and several flowering ornamental plants. The fungus, Botrytis cinerea, most commonly infects and blights wounded or senescent plant tissues. As a blueberry bush blooms, corollas (the fused petal of the flowers) senesce and become quite susceptible to infection.

What are the symptoms? On leaves, brown, irregular lesions develop that sometimes distort leaves. Blighted blossoms turn brown and soon become covered with abundant gray mold. Infected twigs are first brown to black and later become tan to gray. Developing berries can also become infected, but fruit rot usually does not develop until after harvest. Infected berries become covered with a fluffy gray mold.

The fungus Botrytis cinerea causes a decay of ripening fruit. Infected fruit become covered with the typical gray, moldy growth of the pathogen. Botrytis also causes a stem canker which is similar to that caused by other fungi.

Botrytis rot of blueberries