Yes, Weez is right, the rotting and the mold and other diseases, progress more rapidly at the higher temps. What I am saying is that I want the cuttings to take off, and grow roots before this starts. As soon as the end becomes infected then the cutting loses its ability to take up water, and then is more susceptible to any of the above.
The cold, which Weez might not have on the island, slows the cutting down, which allows these things to occur, but doesn't CAUSE them to occur. The cause is the plant pulling these bad things in though the stem, which is unfiltered by the root tissue. There are many cell membranes in the roots that are made to keep the bad stuff out. It grows in dirt but you'll find no dirt inside a healthy stem, the roots are picky that way.
The warmth that I supply just keeps the new cutting at an optimum growing condition, so that the roots can form at the sharp cut end, or the spilt area which some prefer, or the scraped area on the stem. some like. My fav is the node point under the medium that contains cells that are still deciding what they want to be. These can quickly become roots and thus filters to take up what the plant really wants, not just anything available. Example, some color flowers by cutting and placing in dye, with roots to filter this doesn't happen.
Air layering may be the ultimate answer, but far too labor intensive for the numbers I want.
So basically I'm thinking it's a race, between the plant growing roots, and the invasion of whatever might be able to kill it. The temp gives the root development an edge, and that is why I use the distilled water, the cleanest I could think of (free of pathogens) is just another advantage. The rootting hormones protect and encourage, which is another edge.
But I am just an old fart, who found something that works for me, and am guessing as to why it works. Placing the cuttings in a glass or beer bottle filed with clean water(no pathogens) probably protects the stem while it tries to reroot. Plus if it has be sterilized, by your water man, so much the better.
Take with a grain of salt, they are few things in science we know "all" about.
