Stephen Jordan, University of Wisconsin-Madison
Symptoms of peach rosette mosaic virus appear 3 to 4 years after infection. The plant canopy is umbrella-like with shortened and crooked internodes. Leaves are misshapen with a flattened base. Clusters are poorly formed and may shell berries. Bud burst is sometimes, but not always, delayed. Infected vines exhibit reduced vigor and are predisposed to winter injury and death. Vines may die after several years. Over time, a circular pattern of missing or dead vines is commonly observed in mature vineyards. This disease has also been called grapevine degeneration, grapevine decline, berry shelling disease, and delayed budding disease. Boron deficiency and grapevine fanleaf degeneration disease may cause symptoms that resemble this disease.
The causal agent of peach rosette mosaic virus decline is the peach rosette mosaic nepovirus (PRMV). PRMV is primarily a problem in Vitis labrusca, but some cultivars of V. vinifera, and French-American hybrids are also susceptible. Of the varieties of V. labrusca, Concord and Catawba are the most susceptible to PRMV with Delaware and Niagara showing resistance under field conditions. PRMV is also an important pathogen of peaches, and to a lesser degree, blueberries. In addition, several weed species have been shown to be hosts for the virus: dandelion (Taraxacum officinale), horse nettle (Solanum carolinense), and curly dock (Rumex crispus). Infected propagated material is the only means for long distance spread of the virus. Spread within the vineyard is through nematode vectors (primarily the dagger nematode Xiphinema americanum, but also by the needle nematode (Longidorus diadecturus). Grape pomace used for compost in a vineyard can also be a source of the virus, as a small percentage of PRMV can survive hot pressing (60°C for 2 hours) of infected fruit. When infected vineyards are removed, PRMV can survive for a number of years in viruliferous nematodes that feed on infected root material.
Peach rosette mosaic virus, Michigan State University
Photo, European and Mediterranean Plant Protection Organization
Reviewed by Damon Smith, Oklahoma State University and Fritz Westover, Texas A&M University