Bacterial Necrosis of Saguaro in the Low Desert

HOST: Saguaro Cactus, Carnegiea gigantea

SYMPTOMS:

A cactus becomes infected at a wound site. Dark, soft circles appear and enlarge, splitting open and leaking a dark, odorous material. Other infected areas may become dry, crack open, and reveal the remains of dry diseased tissue. Symptoms may appear at any time, but are most likely to be noticed after periods of rain.

CAUSE:

Erwinia bacteria - bacteria can be transferred by the larva of moths, contaminated soil, or contact with a diseased plant

MANAGEMENT:

While the infected area is still small, promptly remove dead, rotting tissue along with ½ inch of healthy tissue. Wrap the decayed material in plastic and dispose of promptly. Slope the bottom of the hole so water will drain out. Wash the hole with a 10% bleach solution, and take care not to puncture healthy tissue. If the lesion is large, girdling or inaccessible, seriously consider removal of the plant. A weakened plant or arm, if large, may fall and cause injury or damage to persons or property.

To Gardening and Landscaping in Maricopa County, AZ