"Autumn Joy" and other purple leaf varieties are also susceptible to anthracnose on rooted cuttings.
Anthracnose ( Colletotrichum trifolit ) symptoms range from a few irregular, blackened areas on resistant stems to large, sunken, oval to diamond-shaped lesions on stems of susceptible plants. The lesions are straw colored with brown borders. Black fruiting structures (acervuli) develop in the bleached lesions and are readily visible with a hand lens. The lesions enlarge, grow together, girdle, and kill one or more stems on a plant.
Infected plants should be removed and discarded. Drench adjacent plants with a fungicide. Start with healthy transplants in a well drained soil, provide balanced nutrition, and avoid over-watering. Grow plants on raised benches to prevent contamination from native soil and start with sanitized pots, flats, and benches.