“Our customers’ pachysandra looks terrible this Spring.” “Volutella blight is rampant this year.” “What to do? Should we just get rid of the plantings?” These calls are common in Extension offices this year. It is true, it is easy to find Volutella fungal leaf blight and stem canker (Volutella pachysandricola) in pachysandra plantings this spring, though it is probable that the disease has been present in many plantings for years.
Symptoms of Volutella blight include tan circular, target-like spots on leaves which brown and die as the disease develops. On stems and stolons grayish water-soaked lesions turn black and then tissue shrivels. Many pachysandra plantings have some Volutella blight, but when large patches of the planting die, pachysandra may turn from a horticultural asset to a liability.
The problem is that the prescribed cultural solutions to the problem run counter to horticultural goals and maintenance practicalities. Common recommendations include: thin the planting, avoid overhead irrigation, and remove diseased and dead plant debris.
Good luck with all that since a dense planting is the point of a pachysandra bed – it often takes years to get there. Above-average cosmic irrigation – rain – is a main factor in the enhanced blight to begin with, and removing dead and dying plant tissue is easier said than done.
So, indeed what to do? Here is one approach that has worked for many over the years. If the problem is severe, mow the planting down to a modest height such that there will be improved air movement in the planting in order to enhance drying conditions. Rake out and remove as much of the diseased and dead tissue as possible (the fungus is a good saprophyte as well as an opportunistic pathogen).
Then, if you and the customer are amenable, use of labeled fungicides, applied according to label directions, applied several times at two week intervals to protect newly emerging growth will hopefully keep the disease down to a dull roar.
Check labels of products containing mancozeb, chlorothalonil, thiophanate-methyl, etc., to see if they may be applied. Remember, labels are historical documents and the actual material you use is your legal guide, not what you remember how a particular product was labeled in the past.