[Arid_gardener] Question from Home-Hort WWW page

[Olin Miller]

----- Original Message ----- From: <llgodin at sasktel.net>
Sent: Saturday, November 11, 2006 9:49 PM
> I have lost my saguaro to bacterial necrosis. What is required to
> disinfect the
> soil before replanting with another saguaro
> in the same spot? Also, does bacterial necrosis affect other plants?
================================================

From:
http://cals.arizona.edu/maricopa/garden/html/t-tips/diseases/saguaro.htm

"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."


  The bacterium "Erwinia bacteria" is very common and is spread by insects
by entering a plant through a wound site and is not specific to the Saguaro
cactus.  But the rot is less common because when it is spread by pollinators
there must be an injury while the plant is in bloom and the pollinators are
active.

  Olin Miller, Master Gardener Volunteer, Maricopa County AZ