Assessment of the Distribution and Occurrence of Dagger Nematodes and Associated Nematode Transmitted Viruses in Pacific Northwest Small Fruit Crops

Abstract

Small fruit production is an important component of the agricultural sector in the Pacific Northwest of the United States (Oregon and Washington). A diversity of small fruits is produced in the region including wine grape, blueberry, strawberry, and caneberry (red raspberry, black raspberry, and blackberry). Plant-parasitic nematodes and viruses both impact the production of small fruits in the region, but there is no up-to-date understanding of the distribution of potential virus-vectoring dagger nematodes ( Xiphinema spp.) and associated nematode-transmitted viruses. Soil and leaf samples were collected from 43 wine grape vineyards, 24 blueberry fields, 23 caneberry fields, 5 strawberry fields, and 1 currant field in 2021 and 2023. The samples were analyzed to determine the presence of dagger nematodes and the nepoviruses tomato ringspot virus (ToRSV) and tobacco ringspot virus (TRSV). Dagger nematodes were found in 52% of the fields. ToRSV was detected in two blueberry fields in Washington, while in Oregon ToRSV was detected in one field each of blueberry, red raspberry, currant, and wine grape. TRSV was not conclusively found in any of the surveyed samples. To our knowledge, this is the first time ToRSV has been reported in wine grapes in Oregon and in the red currant species Ribes spicatum. This study provides an up-to-date assessment of the distribution of dagger nematodes and nepoviruses associated with small fruits in the Pacific Northwest.