Question
We have a very large Saguaro in our back yard.  We've noticed that there was a hole on one side, down at the base of the cactus.  It is black inside but not oozing.  Upon closer look, the "rotting" continues almost all the way around the cactus but with smaller holes of various sizes. The big hole is about the size of a small child fist.  I've contacted local cacti nurseries, hoping someone would come out and tell us what to do.  One told me to carve out the dead "rotting" parts until I get to green or healthy part and spray with 10% bleach.  Another told me to just spray it with 50/50 bleach.  I've contacted the Saguaro National Park here, but was referred to one of the contacted Nurseries.  Oh, by the way, we live in Tucson, AZ.  The Saguaro is on it's original desert level, however the builder built up the ground around the cactus, so in a since, it is in a hole with a grade up from the base of the cactus to the level of the back yard, which I would guess is about a 2 1/2 feet incline.  There is a brick base with wrought iron fence about 21 inches away from the Saguaro. There is a drain in the fence to allow water to escape.  The house was built three years ago.  There are two Mediterranean Palms, 3 year old about 8 feet away from the Saguaro.  One in front and one to the side of the cactus.  The Palms are on a drip system.   The base of the Saguaro is brown about 12 inches up the cactus.  From there up it is green a beautiful.  It stand about 40 feet tall with 5 arms.  What's going on with the Saguaro?  Can we do something to help it out.  We don't want to lose it.  If it falls, it could hit our house, our neighbors house or the brick fences.  Please help us.   Thanks   Roy

Answer
Roy,

Very sorry for taking so long to get back to you (forgot to set my vacation notice). First, who ever landscaped the yard should not have built up dirt around the base of the cactus. This practice (especially with an established root system) can contribute to the plant rotting. The holes are probably being caused by an animal that is eating the cactus. I have heard of the bleach treatment as well, but you may want to use a mixture somewhere in between the 2 recommendations.

I would remove the soil around the base of the plant and replace it with granite or sand, something that does not hold moisture. If there is no black ooze, then it is probably salvageable. You may also want to surround the base of the saguaro with chicken wire (use the wire with the small square holes) to keep whatever is chewing on it away. Hope this helps.

Sincerely,

Greg