Ask the master gardeners
Q: Why is my pachysandra turning brown?
A: Pachysandra is an enormously popular evergreen, spreading groundcover in the Northeast. A member of the boxwood family, it seems impervious to cold, spreads freely and, best of all, it can grow in dense shade. Severe winters and high humidity, however, make the plant subject to leaf blight caused by a fungus, Volutella pachysandrae.
The first signs of the disease are brown blotches on the leaves. These will grow larger until the entire leaf dies. The disease also attacks the stems of the plants, and the entire plant will wither and die. This will appear in patches that often appear circular. In early summer, one can see many tiny pinkish-orange spores on the undersides of the affected leaves and stems. The spores then spread the disease to other plants.
Disease spread is aided by overcrowding of plants, plants weakened by winter drought or injury, wet mulching or insect infestation. The good news is that the fungus really only likes to form on weakened or wounded plants.
If you see in late spring or early summer signs of the brown patches or pink spores, carefully remove the affected plant material immediately, taking care to dispose of it in a manner in which it can do no more harm.
Also be sure to disinfect any tools used in the process in order to avoid spreading the infestation. It is best to do this type of work in dry conditions in order to avoid spreading the disease. This process may have to be repeated during the season in order to get all the infected material.
Although the disease can occur any time during the growth cycle there are steps that can be taken to avoid its occurrence or reoccurrence. Always select plants of the highest quality from a reputable nursery. Take care to thin your existing beds to bring in light and good air circulation. Mulch with an organic mulch no more than 2 inches deep.
Finally, contact your local Cornell office for advice on controlling euonymous scale, the insect most likely to attack and weaken your pachysandra.
Judie Phillips, master gardener with Cornell Cooperative Extension Center of Westchester