Stephen Jordan, University of Wisconsin-Madison
Rugose wood is a complex disease characterized by modifications of the woody cylinder. Four different disorders make up the rugose wood complex: rupestris stem pitting, corky bark, Kober stem grooving, and LN 33 stem grooving.
Within the rugose wood complex, four different diseases can be identified by biological indexing, but only three of them have been associated with viral infection. Rupestris stem pitting is caused by the “Rupestris stem pitting associated virus” (RSPaV); Kober stem grooving is caused by grapevine virus A (GVA); corky bark is caused by grapevine virus B (GVB). LN33 stem grooving syndrome is distinguished by biological indexing, but no virus has been found associated with this syndrome. The viruses associated with rugose wood complex may also occur as mixed infections among themselves and with different grape leafroll associated viruses. Propagation of infected plant material appears to be the primary mechanism of spread for the viruses.
Individual diseases cannot readily be distinguished in the field because of the absence of differential symptoms on various cultivars. In general, affected vines may be dwarfed and less vigorous than normal and may have delayed bud break in the spring. Some vines decline and die within a few years after planting. Grafted vines often show swelling of the scion above the graft union. With certain cultivars, the bark of the scion above the graft union is exceedingly thick and corky and has a spongy texture and a rough appearance, often marked by pits or grooves. These alterations may occur on the scion, rootstock, or both, according to the cultivar/stock combination and possibly individual susceptibility. In most cases no specific symptoms are seen on the foliage, but bunches may be smaller and fewer than normal. Certain cultivars show symptoms similar to those induced by leafroll, i.e., rolling, yellowing, or reddening of the leaf blades. These symptoms, when they occur, are more severe than those induced by ordinary forms of leafroll.
Cultural Management Options
- Plant healthy stock. Use planting material certified free of viruses that cause the diseases of rugose wood complex. Clones of most rootstocks and cultivars that have been tested and found to be free of all known viruses are available.
- There is no way to cure an infected vine. Remove and destroy virus infected vines. Top-grafting is not advisable, as rootstocks will be infected.
- Clean pruning equipment with a 1/10 dilution of household bleach between vines.
Chemical Management Options
Currently, there is no chemical control for the diseases of rugose wood complex.
R. C. Pearson and A. C. Gohen. Rupestris stem pitting. Page 53 in: Compendium of Grape Diseases. The American Phytopathological Society. St. Paul, MN, 1998.
Rugose Wood Complex, University of California
Field Guide for Integrated Pest Management in Pacific Northwest Vineyards, Washington State University
Reviewed by Damon Smith, Oklahoma State University and Ed Hellman, Texas AgriLife Extension