Alternaria - Navel End Rot in the Low Desert

HOST: Navel Orange, Minneola and Orlando Tangelos, and occasionally in Lemons and Limes

SYMPTOMS:

Premature coloring and fruit drop is the best sign of infection. The rot is not always evident on the outside of the fruit. Eventually (frequently not until after harvest) a dark slightly sunken spot appears on the blossom end (as opposed to the stem end) of the fruit. This rotten spot may eventually cover one-fourth of the fruit. The tips of several segments show a dark rot, and the juice of the entire fruit has an unpleasant taste.

CAUSE:

Alternaria alternata a citrus fungus also known as Black Rot. The fungus grows on dead citrus tissue during wet weather. It produces airborne spores which can land and grow on the blossom end of the fruit.

MANAGEMENT:

Keep the tree healthy and minimize stress by a proper maintenance, irrigation and fertilization. Remove infected fruit.