pachysandra subject to blight

Asked April 21, 2020, 3:38 PM EDT

After 4 decades of pachysandra growing around a sycamore tree has suddenly become thiningg and yellow. Don't know the cause or how to fix the problem. The plants were healthy very thick and very green. Fisrt notice the problem starting in February and not cured itself.HELP PLEASE!! Jack

Howard County Maryland

1 Response

We’ve been receiving a lot of questions this spring about decline and dieback of pachysandra. We have speculated that because of our rather mild winter the fungus, Pseudonectria pachysandricola, could have been active during the winter months which would cause increased damage to stems and leaves this spring.
It’s also possible that recent weather extremes (very wet 2018 and spring 2019 followed by drought in 2019) could have also played a role.

The damage is worse in beds where debris such as leaves and branches have fallen and compacted in moisture retaining layers over the pachysandra plants. Therefore, to prevent moisture retention within the plant canopy, do not mulch pachysandra with shredded bark products. New infections will continue through this season if rainfall is adequate. Stressed pachysandra is also more likely to be severely affected. Stresses include plants in a sunny, dry locations, or a planting that was originally in a shady location, but removal of a tree has now exposed the bed to more sun.

Management with fungicide applications without changing cultural conditions is rarely effective since it’s hard to get thorough coverage with the dense foliage and debris layers. Our recommendations are to do extensive thinning and rejuvenation of the beds by string trimming the plants down followed by use of leaf blowers to dislodge the accumulated debris to increase air circulation around the remaining healthy plants. These beds will take time to grow back in and may require fertilization and weeding to return to their former density.