Epidemiology of Grapevine Red Blotch Disease Progression in Southern Oregon Vineyards

Grapevine red blotch disease (GRBD) is an emerging caused by grapevine virus (GRBV). It widespread in most United States winegrape production regions and differential spread dynamics have been reported between the regions. This study surveyed eight vineyard sites southern Oregon over four years for progression of GRBD incidence. The vineyards included five that were or older three three-years-old. incidence blocks ranged from 2.81 to 58.78%, while younger it 0.29 1.11%. Some implemented frequent scouting, removing infected vines replanting. these remained <5% survey period. However, with no roguing replanting, increased nearly 30-fold after years. We analyzed spatial distribution 2020 found highly aggregated based on Spatial Analysis Distance Indices (SADIE). In a separate study, we also tested GRBV infection status asymptomatic next symptomatic inform decision-making when Out 410 surrounding 41 vines, only two positive GRBV. Additionally, 2021, previously identified possible alternative host species: blackberries (Rubus armeniacus) wild/feral grapes (Vitisriparia) collected areas sites. was present 10 70% wild grape samples both 10% blackberry 2020. titer low not detected 2021 samples. These results indicate potential importance as hosts vineyards, unlikely be epidemiological significance.