Eve's needle with rot - HELP!

Trouble shoot problems you are having with your cactus.
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Allynn
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Joined: Mon Jun 19, 2017 2:34 pm

Eve's needle with rot - HELP!

Post by Allynn »

I wrote a while back for help identifying my cactus: viewtopic.php?f=3&t=39130
Now I need help to save it.

A few weeks ago a large section on the right broke off with a black ooze. I cut away the damanged area and I thought all was well but, unfortunately, the rot continued. Last week I had to cut off a large section that is into the main part of the plant. The wound is over 3 inches long and if isn't healing over. I'm afraid I need to cut even more but, if I do, there will be a very large exposed area. Is there something I treat it with to stop the rot? I'd hate to lose this plant and I'm afraid to go into the winter season with it in such distress.

Here is a close up of the problem. The rot is continuing at the top.
rot.jpg
rot.jpg (210.41 KiB) Viewed 994 times
Allynn
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hegar
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Joined: Mon Jan 23, 2006 4:04 am
Location: El Paso, Texas

Re: Eve's needle with rot - HELP!

Post by hegar »

I am sorry to see that a rot has gotten hold of your cactus. Unfortunately, I cannot tell, if the rot was caused by a fungus or a bacterium.
However, it is more likely a bacterium. There are more systemic fungicides on the market than bactericides. These can be applied as a spray, covering the top portion of the plant, injected into the plant's body, or via a soil drench.
Looking at the literature, Oxytetracycline or Streptomycin sulfate seem to be the preferred substances.
One bio-control product, with the name of "Actinovate" does contain Streptomyces lydicus from which Streptomyin is derived. Another biological sold under the label "Monterey Complete Disease Control" contains Bacillus amyloliquefaciens and supposedly does fight bacteria that infect plants. I cannot say anything however about the efficacy of these two unrestricted pesticides. I did even read about using Penicillin, a substance obtained from the Penicillium spp. fungi, which may also be employed for the treatment of bacteria infecting plants, but has not been tested sufficiently in plants.
I did locate a chemical called Copper Sulfate Pentahydrate, present in a product called Phyton 35. However, that pesticide is most likely not available to the general home gardener. Another product, named Elixor contains mono- and di-potassium salts of phosphorus acid. It too may not be readily obtainable for people without a Pesticide Applicator license.
Other than what is mentioned above, the only method that might help arrest the spread of the rot would be to cut off the discolored tissue.
Make sure, that you remove at least 1/2 to 1 inch of healthy looking plant tissue in the process, because the microorganism responsible for the rot may already be present in parts of your cactus that still looks healthy. At least for the last cut, ensure, that the cutting tool (knife) has been thoroughly disinfected. You can use either heat, bleach, or alcohol to achieve a sterile knife blade surface. Before the cut it dry, you could apply a fungicide/bactericide to the fresh cut, then let the cut heal and form a protective callus. Do not allow soil to splash onto the fresh cut. It could move the pathogen right back onto the plant, causing a re-infection.
I wish you the best of luck with the treatment of your cactus patient.

Harald
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