Itasca Grape.

2020-21 Rapid Ag: Determining Distribution, Impact, and Management Options for Grapevine Trunk Disease in Minnesota Vineyards

April 3, 2019

Principal Leader

Matthew Clark

Department

Department of Horticultural Science

The Problem

Grapevine trunk decline is a leading cause of revenue loss for Minnesota grape and wine producers, a $80 million per year industry. For example, one vineyard in Wabasha County reported a 50% loss in grape yield in 2018 due to dying or unproductive grapevines. Another farmer near the St. Croix River reported plans to replace 1500 dead or dying vines (10% of vineyard) in 2019, resulting in a 5-year loss to wine production and considerable re-planting costs. These are common stories in the Midwest grape industry. Research efforts are immediately needed to address this problem before it becomes more widespread and devastates the new grape growing industry.

Background

Grapevine trunk decline is a leading cause of revenue loss for the growing Minnesota wine grape industry, and accounts for substantial losses in grape yield every year. Grapevines take up to 5 years to come into full production; thus the costly act of replacing dying vines due to trunk decline substantially decreases grape production and revenue. What is causing grapevine decline in Minnesota is not well understood. Growers have historically attributed this vine die-back to winter injury, even with cold-hardy varieties introduced by the University of Minnesota. Recent observations have raised strong concern among growers and viticulturists that trunk decline in Minnesota may actually be due to an emerging global problem called Grapevine Trunk Disease (GTD). GTD is caused by several new pathogens, alone or in combination with winter damage. There is added concern that nursery stock brought into vineyards is a source of contaminated vines. Preliminary investigation indicates that GTD is present in Minnesota. However, its prevalence and impact on the industry are unknown. Research is needed to identify the pathogens, determine their impact, biology and ecology and develop necessary management recommendations to vineyards, with the goal of minimizing revenue loss due to grapevine death.

Project Goals and Objectives:

  1. Identify and determine the etiology of GTD-causing species present in Minnesota vineyards, with a focus on determining their prevalence and distribution throughout Minnesota’s wine growing regions
  2. Characterize symptomology (cankers, plant decline) and signs (fruiting bodies and spores) associated with the different pathogens that cause GTD in Minnesota
  3. Survey nurseries that grow and distribute cold hardy grape varieties for GTD on bare root nursery stock, and test the efficacy of heat treatments recommended for GTD eradication on nursery stock
  4. Use the research findings to create UMN Extension recommendations on how to manage and minimize grapevine decline, for growers of cold hardy grapes and grapevine nursery stock
  5. Develop a library of reference samples and optimized molecular procedures that can be used by disease clinics for rapid detection of GTD