During the recent boxwood blight scare the Plant Diagnostics Lab at Rutgers University was flooded with samples of possibly infected boxwood awaiting their final word, but along with those specimens came bits of diseased pachysandra. The fear, they supposed, was that homeowners and arborists thought the pachysandra were suffering from some disease that could possibly be transmitted to their boxwoods. And while it is fairly common for pachysandra to be infected by Volutella pachysandrae fungus, causing Volutella blight, these pachys were ailing from Alfalfa Mosaic Virus (AMV). There is a species of Volutella fungus that causes cankers and dieback on boxwoods, but the patterns on the pachysandra samples were inconsistent with the fungus.
AMV presents as chlorotic rings and irregular blotches on pachysandra leaves. This disease is most commonly spread by the green peach aphid but can also be transmitted by 14 other aphid species. Sap and seeds from infected plants are also mechanisms for spreading AMV. This virus does not prey solely on pachysandra, it is known to be a generalist infecting over 600 plant species in 70 families. So, continue to vigilantly monitor other landscape plants for strange leaf spots and aphids.
Green peach aphids are known vectors of AMV, but 14 other species can also transmit this disease to landscape and garden plants.
Irregular chlorotic spots are a hallmark for AMV, make sure to monitor all your landscape plants as this disease can be pervasive.
AMV will most likely not kill infected plants, control may be accomplished by simply removing diseased portions or individuals. The virus is also present in the sap, so make sure not to wound plants if you are removing them. Contact your arborist to confirm a suspected AMV diagnosis or the presence of aphids, you can then discuss the best method to gain control over this disease if, in fact, it is present on your landscape.
