I have only rooted oleander cuttings in sandy soil.

If you want to start cuttings that have a rot or fungus problem wash them in common bleach. UC Davis general information on stem cuttings says 10 seconds.

Some say dilute the bleach. Some say use hydrogen peroxide. In articles on propagation more attention is made to sterilizing the cutting tools than to sterilizing the cuttings. Some commercial rooting compounds have a fungicide in them.

Here is a link that might be useful: UC Davis general information on stem cuttings.

Thank you, that is a useful link. I think I will try a bleach wash next time. I have already identified the size and position of the cutting material that roots quickest so the solution to my problem may be to concentrate on the easy material and to discard the rest. I'm trying to root about 100 cuttings quickly at minimum cost and effort.