In its 2019-20 fiscal year, the Oregon Wine Board of Directors granted $417,000 to researchers for nine projects with the potential to advance quality grape growing and winemaking in Oregon. The update below is part of a series to let you know about the status of these projects.

Dr. Achala KC is an assistant professor of plant pathology in the Department of Botany and Plant Pathology at Oregon State University, specializing in tree fruit and wine grape pathology. She has prepared the update below. Her co-investigator on this project is Dr. Jay Pscheidt, also of OSU.

Grapevine trunk diseases in Oregon vineyards: A pilot project on epidemiology and management

Project objectives:
In 2019, we initiated a project on grapevine trunk diseases (GTDs) with the objectives of:

  • identifying fungal pathogens associated with grapevine trunk disease in Oregon;
  • understanding if the different climatic regions in Oregon influence the spore dispersal of the most common trunk disease pathogens in Oregon vineyards; and
  • comparing different cultural practices while pruning to minimize availability of primary inoculum to cause grapevine trunk disease.

Importance to the Oregon wine community:
There is evidence of GTDs in Oregon, including Black Foot Disease, Botryosphaeria dieback, Eutypa dieback, Esca, and Petri disease with at least 16 different fungal pathogens based on samples submitted to the OSU plant clinic. There is a lack of information on which GTDs are commonly found in Oregon vineyards, what their associated fungal pathogens are, and the distribution of these diseases.

Furthermore, it is unknown how Oregon’s climate impacts the occurrence of these pathogens. Different climatic regions provide unique opportunities for grapevine trunk disease pathogen development, which may require different methods of management. Therefore, we proposed research to better understand what each of these growing regions is facing in terms of trunk disease by initiating a pilot project in vineyards of the Willamette Valley and Southern Oregon.

Progress so far:
For the first year of this project, we surveyed 16 vineyards in Southern Oregon and 15 vineyards in the Willamette Valley. Vineyards were chosen based on a history of grapevine trunk disease and age of the vineyards.

The symptoms of each flagged vine were recorded. Some vines appeared to have stunted growth and/or yellowing or reddening leaves while other vines appeared healthy. All flagged vines are currently being sampled in each vineyard.

In order to determine the dynamics of spore release at two climatically distinct regions in Oregon, two Burkard volumetric spore traps (Burkard Scientific, U.K.) were set up in vineyard blocks in the Willamette Valley and Southern Oregon. The spore traps were installed at the beginning of December 2019. Sixty-four spore trap samples (32 samples from each site) have been collected to date, which are processed and stored at -80C. This process will continue throughout the 2020 growing season.

Weather stations near the locations of the spore traps will also be monitored in order to determine the correlation between weather variables and the quantity of spores trapped for most common fungal pathogens.

Next Steps:
Once we have baseline data from spore traps, we will compare different cultural practices while pruning to minimize availability of primary inoculum starting in 2021 pruning season.