This looks like an outbreak of a common disease called Volutella Blight. It is not uncommon for Pachysandra, along with Boxwoods, to contract this fungal disease when conditions are conducive to infection, which tends to occur in years with wet spring weather.

Although it may seem drastic, the most practical approach to management is to mow-down the planting to remove the current foliage, rake-out all debris and any accumulations of fallen tree leaves (or dead Pachysandra leaves), and let the patch regrow at its own pace. Monitor the planting for watering needs given our current ongoing drought, especially if the Pachysandra is growing in the root zone of a mature tree, since the tree's roots are competing with them for water. Pachysandra with leaf infections whose roots are otherwise healthy should regrow from this rejuvenation process just fine. Use of a fungicide is not recommended, nor would it be able to cure existing disease.

If you are open to it, we encourage gardeners to remove and replace Pachysandra instead, since it can be invasive in our region along with other popularly-grown evergreen groundcovers like English Ivy and Vinca/Periwinkle. Our newly-updated Groundcovers web page provides some ideas for alternatives, though the plant lists it includes are not exhaustive.

Miri