Hellebore plants, also known as Christmas roses or Lenten roses, can be affected by root rot, stem rot, and rhizome rot. These issues can be caused by fungi like Pythium, Phytophthora, or Rhizoctonia, and can be encouraged by waterlogging. Here are some signs and treatments for these issues:

• Root rot: Signs include yellowing leaves, wilting, and a foul smell near the soil. To treat, you can remove the plant from the soil, shake off excess soil, and inspect the roots. Healthy roots are firm and white, while infected roots are brown and mushy. 
•  To prevent future rot, water the plant in balance and allow the soil to dry out between waterings.
• Stem rot: In the spring, healthy leaf stems can develop basal brownish or blackish rotten spots, causing shoots to fall over. To treat, you can apply fungicides.
• Rhizome rot: This issue can affect leaf stems in the spring.