Symptoms:
The key symptom of walnut blackline disease is a gradual girdling by a narrow, black, necrotic strip of cambium and phloem tissues at the rootstock-scion union, resulting in decline and death of the English walnut scion. On English walnut propagated on paradox rootstock, the disease develops an extensive necrosis of bark in the rootstock that is delineated by the scion at the graft union (Mircetich & Rowhani 1984). Information about symptoms on other hosts is given by the Crop protection Compendium (2005).
The virus:
Cherry leaf roll virus has bipartite genome, RNA and belongs in the genus Nepovirus. It is transmitted by mechanical inoculation, grafting, pollen and nematodes. A detailed description of CLRV is provided by Büchen-Osmond (2003).
