Hi Jeff,

From the photos, this looks like a fungal disease. With all the spring rains we've been having, conditions have been cool and wet, which is optimal for fungal growth on plants. Did you just notice these symptoms this spring? If so, I would recommend removing and discarding the affected foliage. By doing that, you should be able to contain the spread, particularly if the weather warms/dries up. If wet weather persists, you can also consider applying a fungicide in weekly intervals. However, it would be best to confirm that this is a fungal disease before applying fungicides. This can be done by submitting a sample to the CSU State Plant Clinic in Denver (more info here: https://agsci.colostate.edu/agbio/plantclinic/).

Here is a helpful resource for more information on fungal disease: https://hortnews.extension.iastate.edu/1993/6-23-1993/ivyspot.html.

Thanks,

Hania