New closterovirus in ‘Redglobe’ grape causes decline of grafted plants

In California, first-generation table grape vineyards were planted on their own roots. But in recent years growers have been replanting onto acreage previously in grapes more often. Grafted plants are being sought to overcome nematodes and other site-related problems. We investigated the etiology of the decline and death of ‘Redglobe’ table grape scions propagated on different rootstocks, using a series of greenhouse and field experiments, and reverse transcriptase-polymerase chain reaction (RT-PCR) assays. We determined that a specific graft-transmissible agent was closely associated with declining young grapevines. The ‘Redglobe’ closterovirus that we identified was given the trivial name Grapevine rootstock stem lesion associated virus (GRSLaV).