Why are the leaves on your endurio viola turning black?

Black leaves on your endurio viola could indicate a few issues, such as fungal infections like black spot or powdery mildew, which thrive in humid conditions. Overwatering or poor drainage may also lead to root rot, causing leaves to darken. Additionally, exposure to extreme temperatures or nutrient deficiencies could contribute to the problem. It's important to assess the plant's environment and care routine to determine the exact cause.