Foliage growing in black color in places. I have downloaded a photograph, hope you can help. I have had fabulous displays for the last five years here in Sweden.
We did not receive the image.
Poppies can be susceptible to Downey Mildew, Grey Mold, Powdery Mildew, Tomato Wilt Virus, and Rhizoctonia Root Rot.
Without seeing the plants or leaves, and the time of year, I would suspect a fungus disease of some type.
Clean up and dispose of any dead leaves to prevent spread of disease.
Avoid water splashing onto the leaves with overhead watering and apply a fungicide to the remaining plants on a cool, overcast day.