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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Research Project #442941

Research Project: Characterization and Epidemiology of Grapevine Trunk Diseases (GTD) in Idaho

Location: Horticultural Crops Disease and Pest Management Research Unit

Project Number: 2072-22000-046-026-G
Project Type: Grant

Start Date: May 1, 2022
End Date: Oct 31, 2024

1. Survey vineyards in Idaho for grapevine trunk diseases (GTD). 2. Conduct spore trapping to determine the population dynamics of spores of key GTD pathogens, powdery mildew and Botrytis cinerea.

Grapevine trunk diseases will be surveyed in Idaho using a combination of direct molecular testing of grapevine trunk material and soil using real-time PCR assays as well as isolation. Vineyards will be scouted and sampled on two separate occasions during the growing season and isolations will be attempted from symptomatic. Isolations will be conducted at both 20 degrees C and 28 degrees C and representative cultures will be characterized using DNA barcoding (ITS) and additional barcodes such as calmodulin, histone, elongation factor and beta tubulin as required. The pathogenicity of representative GTD isolates will be determined using a small-scale shoot assay in the greenhouse. Real-time PCR (TaqMan) assays will be used for direct molecular testing for key GTD pathogens. All symptomatic vines will be tested as well as up to five asymptomatic vines from each vineyard using real-time PCR assays. Assays for Phaeomoniella chlamydospora, Phaeoacremonium minimum and Eutypa lata will be used initially followed by further assays selected based on the results from culturing and DNA barcoding. In addition, soil will be sampled from each vineyard and DNA will be extracted from 300 g of soil using a previously published method (Woodhall et al., 2012). The soil sample will be tested for key Cylindrocarpon-like anamorphs in the first instance which are implicated in black foot disease of vines using real-time PCR. At two vineyards in southwest Idaho, multi-vial cyclone samples will be deployed to spore trap from mid-May. Spores will be processed weekly for grapevine powdery mildew (Erisphe neactor) and B. cinerea, and results displayed two days after sampling on a new Idaho crop health ‘dashboard’ website. A new real-time PCR assay will be used for E. neactor detection with additional sensitivity. The laboratory already conducts spore weekly spore trapping for potato and sugar beet diseases and hopes to extend this effort to hops and vines for 2022. Automation exists in the laboratory to ensure rapid turnaround of results.