A UNIQUE METHOD OF COMBATING ROT
About twenty two years ago, I translated an article in French from a Belgian journal called 'CACTUS' in which one person's unique method of saving a plant of Opuntia robusta ("Tapuna Pear") from total destruction by rot was described. Noting a large patch of rot on her plant, the lady got the idea of injecting common 2% aqueous mercurochrome from her medecine cabinet into the patch with a hypodermic syringe. The fluid quickly diffused throughout the rotten tissue, arresting its further development and it dried up. The plant survived in good condition, albeit with a dried-out cavity.
Later attempts by others with the same solution did not always succeed and, thinking that this was due to the histological differences between plants and animals, one experimenter, faced with a potentially serious loss of plants after a storm, tried a solution of 5% mercurochrome in 45% ethyl alcohol . He excised the rot from affected plants and he painted the exposed tissue with the 5%/45% solution. All of the plants so treated survived while nearly all of those untreated did not. Several Euphorbias healed themselves.
I have used this latter method a good many times since 1979, especially on some specially valuable plants which I could not have otherwise replaced. My best example of its success is an Echeveria laui, one of the Tropical Hens-and-Chickens, which had only recently been released to the market in 1983. It had rotted from my carelessly having allowed water to collect at the base of the lower leaves. I noticed this just as the rot had reached the third- or fourth-newest whorl of leaves and I immediately cut the stem at that point, leaving only four of the smallest leaves. I then painted the cut surface with the 5%/45% solution, dried it off for several days until scar tissue had formed, and I carried out standard re-rooting procedures. The plant survived (see photo) and it went on to thrive and to win prizes for its beauty. Several years later it again rotted because of a leak from the greenhouse roof and I recovered it just as promptly and as well by the same method.
It is always especially gratifying to note, when I treat an infection which visibly is travelling up through the vascular bundle of some cactus, that the mercurochrome diffuses quickly all along the affected section of each vein until it reaches unaffected tissue. As a result, a cutting taken from an affected plant, treated and dried, even if not all of the rotted veins have been excised, can immediately begin to form new roots while it is fully protected from any new infection by the residue of the mercurochrome.
Kept in a tightly stoppered bottle, 25ml (about 1/2 oz.) of the 5%/45% solution lasts for years and provides a quick and dependable cure for any fast-acting case of rot in valuable plants.