Survey for viruses of grapevine in Oregon and Washington

Grapevines (Vitis spp.) in Washington and Oregon were surveyed for the prevalence of key grapevine viruses. Samples collected from 1,522 vines in Washington were tested for Rupestris stem pitting associated virus (RSPaV), Grapevine fanleaf virus (GFLV), Arabis mosaic virus (ArMV), Tomato ringspot virus (ToRSV), and Grapevine leafroll associated virus-3 (GLRaV-3). Tests were also conducted for GLRaV-1 and -2 on 420 samples from Washington. Two hundred forty samples collected from wine grape vineyards in Oregon were tested for GLRaV-1, -2, and -3, and an additional 2,880 samples were collected from 40 vineyards known to have high populations of Xiphinema americanum nematodes. The latter were tested for ArMV, TbRSV, and GFLV. GLRaV-1, -2, and -3 were detected in 2.6, 0.2, and 6.5% of the Washington sample, and in 3.0, 0.4, and 4.4% of the Oregon samples. RSPaV was detected in 4.6% of the samples from Washington. No ToRSV. ArMV, or GFLV was detected in any of the samples from Oregon or Washington. Transmission of field isolates of GLRaV-3 from Washington by the grape mealybug also was demonstrated.