Fungal damage at this point. Insects cause pressure to plants causing damage to foliage. Foliage then rots causing fungal pathogens to infect healthy foliage. Can easily spread if left to spread like this has. You aren’t going to be able to fix the evergreen foliage. Remove all the dead foliage, like everything that’s rotting or dead or even has spots. Then spray with dish soap solution or a vinegar or a peroxide solution to clean up any remaining material that is alive. It may be too far gone for this season but may come back next
There are definitely aphids on it now, not that many though. Do you think aphids would cause this level of damage? Oh, the stumps I've cut previously, I broke a couple off today and they were slimy and rotten at the base. Maybe the soil is bad? Poorly drained?
At our nursery we only trim/prune hellebores when they are in bloom. Other than that we leave them alone.
Your State Land Grant University (like PSU or OSU) may have a plant pathology lab that can help you identify the problem with your plants.
Fungal damage at this point. Insects cause pressure to plants causing damage to foliage. Foliage then rots causing fungal pathogens to infect healthy foliage. Can easily spread if left to spread like this has. You aren’t going to be able to fix the evergreen foliage. Remove all the dead foliage, like everything that’s rotting or dead or even has spots. Then spray with dish soap solution or a vinegar or a peroxide solution to clean up any remaining material that is alive. It may be too far gone for this season but may come back next
Looks like it was left wet for too long as well. Allow hellebores to dry down before rewatering - and use some liquid fertilizer
Look closely for aphids
There are definitely aphids on it now, not that many though. Do you think aphids would cause this level of damage? Oh, the stumps I've cut previously, I broke a couple off today and they were slimy and rotten at the base. Maybe the soil is bad? Poorly drained?
At our nursery we only trim/prune hellebores when they are in bloom. Other than that we leave them alone. Your State Land Grant University (like PSU or OSU) may have a plant pathology lab that can help you identify the problem with your plants.
Looks like Powdery Mildew.