Brunnera 'Jack Frost' has blackening leaves
We have had a lot of rain in NYC this summer and it seems to have affected my Brunnera 'Jack Frost' which was looking very good at the beginning of the summer. Now it has black spots and black edging on the leaves. The black areas are very thin and crumbly. Is this a problem I should be dealing with? Should I remove the blackening leaves? I am not sure what this is or how I can protect this plant.
Thank you for your recommendations.