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

The groundcovers in the plant lists on the web page you're referring to mention when the plant is evergreen (in the "comments" column of the tables). Not many perennials are evergreen in Maryland, which is probably one reason that the non-native Pachysandra, English Ivy, and Vinca became popular groundcovers. The tables also include a column for "deer browse risk," rating the plants as average (palatable) or low-risk (not often browsed). No plant is deer-proof, as they will taste or eat anything when they are exploring or hungry.

The phlox pictured at the top of that page was photographed at Longwood Gardens in Pennsylvania, in their native plant woodland area. It is only about a foot high in flower; about half that or less when the flowers are spent and just the foliage is present.

Whether cultivars count as "native" is a contentious subject among native plant enthusiasts and biologists. There is no easy answer. A cultivar is a cultivated variety, and it might be propagated from seed (which preserves a bit of genetic diversity), but usually cultivars are propagated by cloning the plant, which keeps the traits that define that selection (flower color, mature size, bloom time, disease resistance, etc.). That propagation is often done via cuttings, division, or sometimes tissue culture in a lab. In that case, all plants bearing that cultivar name would be genetically identical. Gardening with native plants encourages genetic diversity, in part because planting will be more resilient if some individuals have different genetic makeups (they might be more resistant to certain pest or disease issues, weather extremes, and other factors).

The populations of native plants in a given area (say, the piedmont of the mid-Atlantic) have adapted over the centuries to our local conditions and quirks of weather. Their genetics reflect this flexibility and adaptability, so bringing in plants with genetics arising from outside the area (say, several states away) might "pollute" the local gene pool as they cross-pollinate. For species not abundant in Maryland, that might harm local populations if it affects their ability to survive and support any specialist pollinators or seed dispersers.

If the species the cultivar belongs to is native, then some gardeners count the cultivar as native as well. (Some use the term "nativar" as shorthand for a cultivar of a native plant. Where the cultivar originates (where the genes of that particular selection came from when it was propagated) is important, as noted above, but the same holds true for a non-cultivar of the species as well. For example, if a population of Phlox stolonifera (the wild type, not a cultivar) was chosen for propagation from South Carolina and planted in Maryland, those plants might be less well-adapted to our soils, winter weather, and other aspects of the environment. They might bloom out-of-sync with local pollinator activity.

As you can see on the linked map (the lime-green highlighted areas), the natural range of Phlox stolonifera lies mostly outside of Maryland. In comparison, the range of Phlox divaricata (which looks nearly identical to Phlox stolonifera) is broader and encompasses much more of the state. Therefore, both a species and cultivar of a species of native plant could potentially introduce undesirable genes into the local population of native plants, altering their population dynamics. It's probably a consideration more important for species that are relatively rare in Maryland compared to very commonplace species. The ideal would be to plant local ecotypes (plants propagated from seed sourced from local native plant populations), but that is not always available.

Anything that covers the ground to protect the soil from erosion and keep weeds at bay can be considered a groundcover. True, the most popular groundcovers are low-growing and ground-hugging, but that is not a requirement. The plants listed on our Groundcovers page does focus on those which stay fairly low because that is what gardeners tend to use for that purpose.

Which PDF of invasive plants are you referring to? If it's the link we provided to the Maryland Department of Agriculture list of what nurseries are allowed to sell, that is not a list within our control. The MDA is the regulatory agency for such matters, and while they are aware of the invasive behavior of both Butterfly Bush and several other species, they have not updated that regulated list in several years. However, they are currently working on a process to expedite that species review so they can expand the prohibited list to stop garden centers from selling certain species known to be invasive.

Miri

You're welcome!