Caused by a number of organisms, esp. Pythium and Rhizoctonia. The stem becomes blackened at the base and eventually dies. Caused by unhygenic technique using dirty pots, tools and unsterilized compost. Waterlogged compost encourages it.
Use clean equipment, add drainage to the compost and do not overwater. Use mains water as the water in tanks can harbour infection. Remove any affected cuttings immediately and remove leaves which die back.
Use a rooting agent containing a fungicide like Captan or immerse the cutting in a fungacidal solution before planting. Cheshunt Mixture can be used to spray the cuttings during growth.
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