We will check with our plant pathologists for their feedback on the pictured symptoms, but could use more information in the meantime: were the spruce trees (or anything else that might be planted close to the Pachysandra that we can't see in the photos) sprayed with anything (fungicide, insecticide) prior to the symptoms first appearing on the Pachysandra? The damage looks a bit like phytotoxicity, which is plant tissue injury from a chemical exposure, and sometimes phytotoxicity symptoms take a while to manifest after exposure. Aside from a pesticide, phytotoxicity can also arise from salt exposure...is there a walkway or sidewalk that had ice-melt applied near this planting, where snow might have been shoveled onto this garden bed?

If the symptoms were due to infection that arose due to crowded foliage and poor air circulation, we'd expect to see symptoms appear first towards the interior of the patch, rather than on the outer edges. It's not likely to be a root issue, which probably would have resulted in different and more uniform symptoms for the affected plants.

Although trimming off the badly-damaged leaves would be fine to do, since they cannot heal and recover, we don't think you need to dig up any of the affected plants yet, as their roots and crowns might be alive and able to regrow the foliage later this spring. If the damage is due to phytotoxicity, the affected leaves don't necessarily need to be removed since they would not be harboring an active pathogen that's at risk of spreading, and the leaves would disintegrate on their own. Still, removing dead/dying leaves can improve air circulation if you are worried about other infections (such as Southern Blight, but that would not be a risk until summer and hot weather).

Miri

Thank you for the additional information. Our pathologist took a look and isn't certain that this is a leaf spot infection, though if symptoms reoccur on new growth later this spring, we can discuss sending in samples for further diagnosis at that point. In the meantime, this might be winter injury, but he recommends trimming off the areas of dieback and trying to carefully remove the leaf litter that has accumulated within the patch, since it can reduce air circulation, trap moisture, and create conditions more conducive to infections like Volutella Blight (a common ailment of Japanese Pachysandra), Southern Blight, and various fungal leaf spots.

Since the plants don't grow as vigorously as Japanese Pachysandra, we hesitate to recommend the process of mowing-down the entire patch and letting it regrow, as we would for a patch of Japanese Pachysandra that developed a Volutella outbreak. Plus, the plants will be blooming soon (in a few more weeks), and a rough raking or haphazard trimming with a string trimmer could remove all of those buds. (Not necessarily harmful to the plant to deny it a bloom cycle this year, but aesthetically not desirable, and it would deprive wildlife of the flower resource.)

Feel free to send us an update on the plants as they begin new growth later this season, if they appear to still be symptomatic or worsening in another way. Sometimes root rot kills well-established patches of Allegheny Pachysandra if the drainage isn't good or if they stay too wet, and our summer heat might also stress them since they are not locally native (they occur wild in the southern Appalachians, where at elevation the summers are a bit cooler overall, especially overnight).

Miri

You're welcome!