—by Melissa Hansen, Washington State Wine Commission

Research into soil health’s role in vineyard sustainability is growing with the June 2023 planting of a 4-acre trial vineyard featuring Chardonnay and Cabernet Sauvignon on a variety of rootstocks and with a variety of soil management practices. The long-term research site at Washington State University’s Irrigated Agriculture Research and Extension Center in Prosser is supported by the Washington Soil Health Initiative and the Washington State Wine Commission. (TJ Mullinax/Good Fruit Grower)
Research into soil health’s role in vineyard sustainability is growing with the June 2023 planting of a 4-acre trial vineyard featuring Chardonnay and Cabernet Sauvignon on a variety of rootstocks and with a variety of soil management practices. The long-term research site at Washington State University’s Irrigated Agriculture Research and Extension Center in Prosser is supported by the Washington Soil Health Initiative and the Washington State Wine Commission. (TJ Mullinax/Good Fruit Grower)

Sustainability is a top research priority for the Washington wine industry. While the overall objective of all research is to improve wine quality by addressing high-priority vineyard and winery issues, in recent years, the focus has shifted to finding sustainable, long-lasting solutions to these problems.

Washington wine is sustainable by nature. A combination of factors in Eastern Washington — arid climate, warm temperatures, low humidity, persistent winds and pest-killing winter freezes — generally results in low foliar disease and insect pressures and less need for pesticide applications. The ability to apply fewer fungicides for grape powdery mildew than in other wine regions is a great benefit, but there are other challenges to be addressed and more tools to be developed to keep vineyards viable for the long term.

Sustainable research 

Of the 18 research projects for 2024–25, funded through the Washington State Grape and Wine Research Program and the Washington State Wine Commission’s own research program, more than half are related to sustainability and keeping the wine industry competitive, productive and viable. Following are the goals of currently funded projects that relate to sustainability:

—Irrigation: Evaluate soil water sensors to optimize irrigation scheduling and water use efficiencies; quantify soil water availability and total soil water content. 

—Cold hardiness: Develop best management practices to winterize grapevines; collect and evaluate cold hardiness data.

—Wildfire smoke exposure: Develop mitigation tools for wineries; create a sensor network for vineyards to help predict risk; develop vineyard barrier sprays to reduce grape uptake of smoke compounds.

—Weed management: Integrate mechanical, chemical and alternative weed management options to develop successful, long-term weed management strategies.

—Pest management: Develop long-term integrated pest management strategies through rootstocks for nematode and phylloxera; evaluate canopy management and UV-C light to suppress powdery mildew and avoid fungicide resistance; assess grapevine phytotoxicity of bloom and midsummer fungicide applications. 

—Grape mealybug: Evaluate efficacy of mating disruption for sustainable control of grape mealybug, which transmits grapevine leafroll disease.

—Grapevine leafroll disease: Learn if mating disruption can effectively slow the spread of leafroll disease; investigate correlation of co-infection of different viruses and spread of leafroll disease. 

—Decision Aid System:Develop a web-based format for crop protection data contained in the Field Guide for Integrated Pest Management in Pacific Northwest Vineyards and create a Decision Aid System platform to integrate a crop protection database for future decision tools. 

—Soil health: Quantify long-term soil management options (mowing, cover cropping, compost) on soil health metrics and the impacts on young vine establishment and grape quality; establish best management practices to improve soil health.

Why the sustainable focus?

The grape and wine research program in Washington is driven and guided by the industry. Research priorities, developed by the state’s wine grape growers and vintners, determine the direction of the research program. In recent years, vineyard sustainability has ranked a top research priority in the annual research survey conducted by the Washington State Wine Commission. Before 2021, pest and disease management and mechanization/precision viticulture were ranked at the top of viticulture research priorities. 

The research priority list is important because it helps researchers focus on topics most important to Washington growers and winemakers, and it helps keep research relevant to the needs of the industry. 

Another reason for the sustainable focus is Washington State University scientists’ recognition of the wine industry’s need for sustainable management strategies that will keep the state’s wine grape production competitive in the future. 

Such tools are needed by all growers, including those participating in the Sustainable WA wine grape certification program that was launched in 2022. Sustainable WA is the first statewide, certified sustainability program built specifically for Washington vineyards. It signifies the industry’s commitment to quality fruit, environmental stewardship, healthy communities, human resources and economic viability.

Solutions

In today’s complex world, there are few stand-alone fixes, but I wanted to share two recent examples of research findings that are helping Washington wine become more sustainable. 

First, in a study about nematode management, led by Michelle Moyer, WSU Extension viticulture specialist, the success of soil fumigation to control northern root-knot nematode in own-rooted replant situations was found to be short-lived. Root-knot nematode populations began to rebound six months after fumigation treatment; and by 18 months, populations were at pretreatment levels. 

Second, Doug Walsh, WSU IPM coordinator, found that, in some locations, grape mealybug now shows resistance to neonicotinoids, such as imidacloprid, which makes management more difficult and costly. He’s now exploring the potential to use mating disruption with sex pheromones as a sustainable tool that won’t have resistance issues. 

As we tackle major vineyard challenges such as grape mealybug and leafroll virus, fungicide resistance, hot and cold weather extremes, weed management without glyphosate, replanting vineyards in nematode- and phylloxera-infested soils, and more, scientists are evaluating the combination of tools for long-term solutions. These options integrate a variety of strategies, from genetics and plant improvement to chemical, mechanical and cultural practices. The Washington wine industry doesn’t have the financial depth to solve the same issue repeatedly, thus, research must take a holistic approach and use tools that work together. 

Research related to sustainability goes beyond certification programs. Sustainable research is of value to all Washington wine grape growers interested in long-term solutions. •

Save the date for WAVE

The Washington State Wine Commission and Washington State University’s viticulture and enology department will combine educational and research seminars at the 2025 WAVE (Washington Advancements in Viticulture and Enology), scheduled April 23 at the WSU-Tri-Cities campus. The daylong event will feature sustainability research and solutions for winery and vineyard problems, research poster displays and lunch. The event will conclude with a wine social hour. The keynote speaker will be part of the Ravenholt Lecture Series. 

The Albert Ravenholt Lecture Series brings experts from the grape and wine industry to WSU to share their research and professional perspectives. The series is made possible through an endowment from the Albert R. Ravenholt Foundation. Ravenholt, an early pioneer in Washington’s wine industry, was founder of Sagemoor Vineyards. WAVE, the signature research event of the Washington wine industry, highlights cutting-edge research and connects growers and wineries with scientists.