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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #115844
Title: DISCOVERY OF NEW GRAFT-TRANSMISSIBLE AGENTS CAUSING DECLINE OF YOUNG GRAPEVINES

Author
item Uyemoto, Jerry
item ROWHANI, A - UNIV. CALIF., DAVIS
item LUVISI, D - UNIV. CALIF., DAVIS
item KRAG, C - FORMER ARS EMPLOYEE

Submitted to: California Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: New grape viruses associated with graft-incompatibility were detected by using a panel of different rootstocks representing different species. Two different graft-transmissible agents (GTAs) were found in a panel of 9 rootstocks. One GTA was isolated from cv Redglobe and was identified as a closterovirus belonging to the grapevine leaf roll closterovirus type 2 group. However, it did not cause leaf roll symptoms in Cabernet sauvignon or Cabernet franc (standard indicators for leaf roll disease). These results should lead to identification of additional biological indicators for use in registration and certification clean stock programs.

Technical Abstract: When the grape rootstock AXR#1 dominated wine grape plantings in California, there was little or no mention of graft- incompatibility or decline of young plants. However, as phylloxera overcame AXR#1's weak resistance, the extensive commercial use of alternative phylloxera resistant rootstocks with parentage differing from AXR#1became a reality. Concomitantly, there was a rise in grower complaints of small, weak-growing and dying/dead grapevines in young vineyards. In some instances, the fungal pathogens Cylindrocarpon obtusisporum and three Phaeoacremonium species were demonstrated to be the causal agents of black-foot and grapevine decline diseases, respectively. In others, a similar cause and effect association was lacking. While investigating the etiology of decline/death of Redglobe table grape scions propagated on different rootstocks, we determined that a specific graft-transmissible agent (GTA) was closely associated with declining young grapevines. In addition, a second GTA, also responsible for young grapevine decline/death, was found.