My pachysandra is looking weak, turning a yellowish green and losing leaves.
Answer
When these problems occur in late winter/ early spring, there are a number of things that can be going on with your pachysandra, but often it is damage after a difficult winter season or overexposure to light before the sheltering tree leaves re-emerge. After winter, pachysandra has frequently been covered with snow or wet leaves and deprived of sunlight for a period of time. For a plant that stays green through the winter, extended snow cover with attendant crushing of stems and deprivation of light is a significant set back. Winter damage to pachysandra and other evergreen plants from snow or wind is very common in our area. Remove any remaining leaves or debris from the planting bed and there is a good chance that you will see healthy new growth emerge as the growing season resumes, with increased hours of daylight and warmer temperatures.
When the damage is observed in the late spring or summer, the most common disease of pachysandra is leaf blight caused by the Volutella pachysandrae fungus. This infection occurs during damp parts of the growing season. This is an excellent Cornell University College of Agriculture Fact Sheet on this disease that includes photos so you can see how it looks on a plant and compare it to what you have noticed in your garden. It also details management strategies, which include thinning of plants to improve circulation and removing and destroying severely affected plants.
Having your soil tested through your county's cooperative extension lab is a worthwhile endeavor so that you uncover any underlying nutrient deficiency or soil pH issue affecting your pachysandra. In spring, amend your garden beds with compost for improved soil texture and nutrition that will reduce the likelihood of disease going forward. That will help your plants more than any fertilizers. Fungal diseases are apt to pop up in older garden beds where planting gets crowded and the soil no longer drains well and pachysandra groundcovers are often forgotten parts of the landscape.
Courtesy of NYBG Plant Information Service
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