By Lauren Paterson, 黑料社 College of Agricultural, Human, and Natural Resource Sciences

Grapevine red blotch disease spreads through vineyards and blotches leaves, shrinking wine and juice grape harvests.

Researchers at 黑料社鈥檚 Ste. Michelle Wine Estates Wine Science Center are studying how and why the grapevine red blotch virus, which causes the disease, spreads.

鈥淲e鈥檙e interested in finding out how the grapevines respond to the virus,鈥� said Bhaskar Bondada, 黑料社 associate professor.

Grape leaves work like solar panels, using sunlight to convert sugar into energy that fuels grape production.

Because leaves become less active when grapevines contract the red blotch virus, less sugar is moved through the plant, causing grapes to fade and grow more slowly. The virus also adversely affects pH, tannin levels, and other flavor characteristics of the fruit, and the final wine.

While virologists study the virus itself, Bondada, a physiologist, is interested in how the physical symptoms of the disease manifest on the plant.

鈥淚鈥檓 studying what the symptoms look like in the plant on the cellular level, and how the virus spreads throughout the vine and the vineyard,鈥� he said.

Research team member and 黑料社 Viticulture & Enology graduate student Bailey Hallwachs took samples from multiple vineyards throughout Oregon and Washington over the summer, and is currently processing fruit and plant tissues samples at the Franceschi Microscopy and Imaging Center in Pullman. She uses microscopes to observe grapevine plant cells affected by the virus.

During the six years between her undergraduate and graduate studies, Hallwachs worked as an interior horticulturist at the Cheyenne Botanic Gardens, teaching gardening classes and managing the community gardens.

鈥淐onsistently, the issues we faced in production on a horticulture level were insects and diseases,鈥� she said. 鈥淚 wanted to get my graduate degree at 黑料社 to understand the science behind solving major issues in agriculture so I could be part of the solution.鈥�

The three-cornered alfalfa treehopper, a small green teardrop shaped insect, is the only confirmed insect to transmit the virus to the grapevine plant. There is currently no solution for treating grapevines infected with red blotch virus, aside from removing and replacing affected vines.

黑料社鈥檚 research in red blotch virus is in partnership with Oregon State University. Field researchers at OSU provide the plant tissues and fruit, which are then analyzed at the 黑料社 Wine Science Center.

鈥淥ur OSU partners are doing research in the field, and we are doing research at the physiological level,鈥� Bondada said. 鈥淥nce we have the data for them, we can develop more strategies to control the spread of the red blotch virus.鈥� Research for this project is funded by the Oregon Wine Board and began in the spring. Bondada and Hallwachs intend to share their research in the new year.

By Lori Wollerman Nelson, 黑料社 Tri-Cities

A team at Washington State University Tri-Cities is researching the impact that a type of fungus could have on vineyard growth and associated nutrient uptake, which could lead to less watering and less fertilizer required for a successful grape crop.

Tanya Cheeke, assistant professor of biology, was awarded a $25,000 grant by the Washington State Grape and Wine Research Program to support a series of greenhouse experiments, as well as a two-year $40,000 grant to support a field experiment from the BIOAg program of the 黑料社 Center for Sustaining Agriculture and Natural Resources.

Cheeke is working with graduate student KC Cifizzari and undergraduate Dylan Hartwig on the project specifically to understand the role that arbuscular mycorrhizal fungi, or AM fungi, play in plant nutrition and production for grapevines.

黑料社 85 percent of all plant species, including most crop plants, have an intimate relationship with AM fungi, Cheeke said. The naturally-occurring soil fungus forms a dense network of connections with the plant by inserting tiny threads, called hyphae, into its roots. Through this shared connection, the plant sends food to the fungus and the fungus increases water and nutrients available to the plant. AM fungi usually enhances plant nutrient uptake from the soil.

Cifizzari said they are including phosphorus treatments to see if the grapevines grown with AM fungi do just as well as plants that are only given fertilizer. If grapes grow as well with additional AM fungi and a lack of additional phosphorus as the grapes given only phosphorus, then adding AM fungi could reduce how much fertilizer vineyard managers need to apply to their vines, they said.

鈥淭he nice thing about AM fungi is that they are living organisms and the treatment should be self-renewing,鈥� Cheeke said. 鈥淲ith fertilizers, you have to reapply regularly to get the same effect. That can be expensive.鈥�

Merlot grapes are a popular varietal in Washington and were shown to respond more strongly as part of a greenhouse experiment by Cheeke and her team as compared to another varietal studied – Chardonnay.

Cheeke said the variability between varieties of crops is not uncommon, however, the researchers also caution that greenhouse conditions don鈥檛 necessarily mimic field conditions. Future research will investigate this further. A second greenhouse experiment to evaluate the effectiveness of different commercially-available AM fungi products is ongoing this fall.

鈥淲e will compare the growth of grape vines grown with three commercially-available AM fungi products, soil from a natural sagebrush habitat, and soil from a 50-year old vineyard,鈥� Cheeke said.

The results of this study could help Cheeke know which AM fungi products to recommend to vineyard managers, if results prove successful.

Both Cheeke and Cifizzari are interested in the role that AM fungi could play in sustainable agriculture. Agricultural crops usually have reduced colonization of AM fungi because practices like applying fungicides and tilling the soil can deplete naturally-occurring sources of these fungi. Without their fungal helper, agricultural crops can require more water and fertilizer to be productive and can be more susceptible to plant diseases.

鈥淕rape growers are very interested in the potential benefit of AM fungi, but they need more information to feel comfortable using it.鈥� Cheeke said.

鈥淎dding AM fungi to vineyard soils could be a way to make agriculture better for the health of the land and the people who work it,鈥� Cifizzari said.

By Lauren Paterson, College of Agricultural, Human, and Natural Resource Sciences

Extreme heat, and too much water in response, affects a delicate balance in wine grape quality.

黑料社 researchers are studying the effects of heat, and developing an electronic, open-source cooling system to protect plants and wine quality, supported by the U.S and Washington State Departments of Ecology and recent grant awards from the U.S. and Washington State Departments of Agriculture and the Northwest Center for Small Fruits Research.

Markus Keller, professor of viticulture at 黑料社, is examining the effects of heat stress on grapes.

Heat causes physiological reactions in plants that affect growth rate and sugar content, and ultimately influence the flavor of wine.

鈥淚f grapes develop too rapidly, there will be too much sugar at harvest and too much alcohol in the wine,鈥� Keller said. 鈥淎cidity also decreases with too much heat, making the wine taste bland.鈥�

Vineyards that get too hot can also affect the color of the wine. To predict and prevent heat damage, 黑料社 offers growers an online听听(GDD) tool.

鈥淲e track temperatures and make the data available through GDD,鈥� said Keller. The tool estimates growth and development of plants during the growing season by comparing average heat throughout regions of Washington.

Since 2011, when the GDD tool was launched, each growing season has been unseasonably warm.

鈥淓very year, the average moves up a little,鈥� Keller said. 鈥淚t鈥檚 getting warmer.鈥�

Evaporative cooling in vineyard canopies

Keller is now focusing on mitigating heat stress.

In his research, he discovered that fruit quality is more influenced by temperature than water.

鈥淭hat was something unknown to us before,鈥� he said, and runs against prevailing wisdom.

鈥淲hen we water stress the plant, it grows less. It turns out, the effects of this water deficit in terms of fruit quality is really about temperature,鈥� he said.

To avoid overwatering plants while keeping them cool amid heat waves, Keller and his team have developed a cooling system for vineyard canopies.

鈥淗eat waves in Washington can reach temperatures of 110 degrees Fahrenheit or more,鈥� said Ben-Min Chang, a doctoral candidate in 黑料社鈥檚 Department of Horticulture who works alongside Keller. 鈥淭his is a very hot region.鈥�

Over-watering in response to heat can cause plants to become oversaturated with water.

鈥淚t eventually penetrates to the soil and reaches the roots, which can cause excessive growth out of sync with the normal season,鈥� Chang said.

Chang said the Cabernet Sauvignon grape, which usually has a complex flavor ranging from blackcurrant to cedar, might end up tasting like a green pepper. 鈥淭hat is a sign of excessive growth,鈥� Chang said. 鈥淕rowing grapes is a balancing act. Growers need to ensure their response to heat doesn鈥檛 tip the balance.鈥�

Over the past two growing seasons, Chang developed a mechanized machine to lower the temperature of vineyard canopies.

He used a sensor from an infrared thermometer gun to read the temperature of the canopy, and an electronic micro-controller to activate misters installed throughout the vineyard.

鈥淚 use the micro-controller as the brain, and I use the infrared thermometer as the eye to measure the temperature,鈥� Chang said. The device automatically runs the water misters when the canopy reaches 95 degrees Fahrenheit.

Using a sensor to measure water saturation on canopy leaves, Chang was able to improve his device. When the sensor detects that leaves have reached their saturation point, the mist stops.

To protect his sensors from ultraviolet rays, Chang uses a shiny aluminum wine can.

鈥淎luminum is a great reflector, so the sensor inside is protected,鈥� he said.

The software that runs the electronic cooling system is open source. Chang plans to do the same with his canopy cooling device, so any grower can build their own.

鈥淚t鈥檚 a good way to pay it forward,鈥� he said.

Following this season鈥檚 harvest, both Keller and Chang will see the results of their temperature control techniques.

In preliminary research, the team found that the evaporative cooling technique caused grapes to grow differently.

鈥淭he cooled grapes are already larger than the control group,鈥� Chang said. While the control grapes take the brunt of the sun鈥檚 rays, those cooled with Chang鈥檚 device have fared better so far. Now comes the taste test.

鈥淭his experiment started in the vineyard and will end with us testing grapes and tasting the wine,鈥� Chang said. 鈥淲e鈥檒l be able to see how the heat and evaporative cooling have affected the grapes and their overall quality.鈥�

Wine-making normally takes four weeks after harvest, so Chang hopes to have more answers by the end of the year.

鈥淲e are thankful to the donors who allowed us to continue this important research,鈥� Keller said. 鈥淲e are hoping we can develop our cooling approach as a practical solution for growers and winemakers.

Preliminary research to be scaled into larger effort analyzing trends in wine industry entrepreneurship

By Maegan Murray, 黑料社 Tri-Cities

RICHLAND, Wash. – From renowned winemaking regions to those that aren鈥檛 typically known for winemaking, business faculty from Washington State University Tri-Cities are studying why people start wineries in locations across the United States.

Wine is currently made in every state in the nation; however, there are wineries located in regions that may not be suitable for grape growing or that don鈥檛 have a heavy foundation in wine entrepreneurship, said Rhonda Hammond, 黑料社 Tri-Cities assistant professor of hospitality business and wine beverage business management.

Study examines winemakers鈥� motivations

鈥淭here is a gap in data regarding entrepreneurship in the wine industry,鈥� Hammond said. 鈥淭here hasn鈥檛 been a lot of research conducted on wine entrepreneurship in the United States. Not all winemakers are established in the places best for winemaking.鈥�

Hammond, Byron Marlowe, clinical assistant professor and wine and beverage business management program coordinator, and Paul Skilton, associate professor of management, want to understand winemakers鈥� motivations and analyze major themes in entrepreneurship for wineries across the industry

In spring 2017, the researchers examined 307 U.S. wineries and vineyards as identified by Wine America, the national association of American wineries. They analyzed web and other digital media information to determine why wine makers chose various winery locations, and to see if location impacted success.

Location familiarity may trump best growing climate听

Hammond said their initial research indicates some winery owners, especially for those in regions that aren鈥檛 known for wine, may have sought out locations based on familiarity, regardless of whether the region鈥檚 soil, atmosphere, reputation and other conditions were conducive for winemaking. Others may import their fruit juice from other locations, she said.

鈥淚f people are already familiar with a place, then it makes it easier for them to be aware of opportunities and feel more comfortable starting a business in that location,鈥� she said. 鈥淪ome may also be able to import grape juice. Just because they may not be able to grow the grapes there, doesn鈥檛 mean they won鈥檛 be able to get the juice to produce wine.鈥�

Hammond said wineries located in climates unsuitable for grape growing may also make wine with other fruits.

鈥淭he definition of wine is fermented fruit juice,鈥� Hammond said 鈥淗awaii, for example, is making pineapple wine. With the ability to transport juices, winemakers can utilize materials from other regions.鈥�

The researchers plan to expand their research into a more extensive study where they will reach out to wineries across the country to assemble in-depth information about the wineries鈥� beginnings.

鈥淲e are hoping this can give us some direction and hopefully turn into something much bigger for the betterment of the wine industry,鈥� Hammond said.