Canna lily diseases are caused by various pathogens including fungi, bacteria, viruses, and nematodes. Symptoms range from wilting, yellowing, brown or black lesions, soft rot, and fungal growth. Management involves using disease-resistant cultivars, crop rotation, weed and pest control, removing infected plants, and fungicides. Key disease terms include bulb rot, leaf spot, blight, and wilt. The disease cycle, epidemiology, and diagnostics help understand disease development and spread, as well as identify and diagnose diseases.