New Spray Film for Grapes Cuts Water Need

Oregon researchers slow down water loss and fight pests with food-grade product

by Peter Mitham
Trials at Seven Hills Vineyard in Milton-Freewater, Oregon have helped Oregon State University horticulturist Clive Kaiser develop a biofilm that reduces grapevines' demand for irrigation water by 25%.

Milton-Freewater, Ore. – Water management is a key issue for grape growers, particularly in arid growing regions such as the Columbia Basin of eastern Washington.

Wine grapes may not be the region’s thirstiest crop, requiring about half the water of tree fruits, but they still demand the equivalent of 22 to 26 inches of precipitation each year. A new pumping station on the Yakima River near Benton City has made life easier for growers in the Red Mountain AVA, and further west in the valley the Roza Irrigation District approved a new pumping system after drought conditions restricted water flows to growers in spring 2015.

Those strategies focused on managing supply, but work by Clive Kaiser, an extension horticulturist with the Umatilla County Extension Service and Oregon State University professor attached to the Oregon Wine Research Institute is looking at things from the vine’s point of view.

Building on his work developing a film to protect sweet cherries from splitting, he’s spent the past two years piloting a film that aims to help vines hold on to the water they’ve got. While the danger for cherries is rapid uptake of water, Kaiser wants to help slow down a vine’s water demand.

“Water tables in the Pacific Northwest are dropping, so we have to look at water efficiencies as something for the future,” he said. “So anything we can do to reduce water usage is going to be key to continuing production into the future.”

While the impetus came during the California drought of 2015, the ongoing risk of drought conditions all along the West Coast make it relevant to Oregon, where some Willamette Valley growers are finding themselves short of water.

“People with senior water rights don’t necessarily have as big an issue, but people with junior water rights get turned off,” he said. “The Willamette, for example, they never worried about water in the past because they always had sufficient rainfall, but with climate variation we’re starting to see drier summers and protracted periods without rainfall, and a lot of those people didn’t see the need for applying for water rights back in the day.”

Kaiser’s solution was to develop a film enhancing the plant’s natural cuticle, which regulates evaporation and prevents harmful moisture from entering plant tissues. It is applied via foliar spray.
The previous film, an organic product known by the trademarked name SureSeal, is derived from palm oil and cellulose. Its key component is a hydrophobic copolymer of stearic acid, cellulose and calcium that repels water. The new film, known as HydroShield, includes pectin and other proprietary hydrophilic components.

“The new product is more hydrophilic. It is partially hydrophobic — obviously, you still want to stop water loss through it — but it also allows movement through it because of the inclusion of pectin,” Kaiser explained. “By swelling, [the pectin] holds onto the water, so it’s not just a conduit. It allows movement, but slow movement of water.”

The film was applied using a knapsack sprayer during trials, but is formulated for application with a mist blower or tower sprayer at 0.5% in water. The water evaporates, leaving the film. It can be applied in combination with pesticides, so doesn’t require a separate pass through the vineyard.

Kaiser found that four applications, once every two weeks beginning in late May, was sufficient to cover the foliage as it emerges through mid July. Kaiser estimates the total material cost of the four sprays at about $220 per acre, excluding labor, equipment and fuel costs.

Working with Sadie Drury of North Slope Management LLC, which manages Seven Hills Vineyard and provides services to the massive SeVein vineyard project on the Oregon side of the Walla Walla Valley, Kaiser demonstrated the film’s effectiveness.

Seven Hills Vineyard typically sees 12 inches of rainfall and draws the equivalent of 14 inches of precipitation from irrigation sources. HydroShield reduces the demand by 3.5 inches to 10.5 inches.
“We were able to reduce the irrigation by 25% without impacting on shoot extension, without impacting on yield or quality,” he said.

HydroShield has received conditional approval for use in organic systems as a surfactant at the request of Oregon blueberry growers who think its thickness — about 90 micrometers — may prevent spotted wing drosophila (SWD) from laying eggs. Research into that potential application is undertaken in partnership with Kaiser’s fellow professor and entomologist Vaughn Walton.

HydroShield is made from food-grade ingredients and therefore enjoys an exemption from registration as a pesticide.

Kaiser is seeking a patent for the film, and Oregon State University’s Office for Commercialization and Corporate Development is undertaking negotiations towards securing a manufacturer. Kaiser would like to see the product in farmers’ hands by next summer, though research with the product will continue.
Wine grape research and fermentation sciences is not generally a large area of activity for the university, but Kaiser’s work promises to give Oregon growers and those throughout the region a new tool for managing water use and SWD.

“The climate is really changing and it’s affecting viticulture in the Willamette Valley,” said Mark Chien, program coordinator with the Oregon Wine Research Institute. “Irrigation is in our future. These tools will all become meaningful to growers, eventually.”


Posted on 11.05.2018 - 11:42:04 PST
Hmm pectin instability in wine can be a real problem, I wonder if this will impact the finished product?

Posted on 11.07.2018 - 12:31:12 PST
Finished wine impact is my first consideration since this remains on the ever important skins. Secondly, this is yet another spray application on our food products...employee safety (recent lawsuit) and residuals passed on to consumers needs to be thoroughly tested as well.