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Micronutrients, GAPs, Organics

Posted by | July 27, 2010

A Pinch of This, a Dash of That – WSU Research Studies Micronutrients in Grapes

Doctoral student Suphasuk “Bird” Pradubsuck measures a Corcord grape vine prior to excavating it. Once excavated, she analyzed the plant's parts to determine Concord's micronutrient requirements.
Doctoral student Suphasuk “Bird” Pradubsuck measures a Corcord grape vine prior to excavating it. Once excavated, she analyzed the plant's parts to determine Concord's micronutrient requirements.

When humans don’t get enough Vitamin C, we can get sick with scurvy. The same is true of plants. Micronutrients such as boron, zinc and copper, although only a tiny part of a plant’s diet, can have a profound effect on the plant’s health.

WSU soil scientist Joan Davenport and her colleagues at the WSU Irrigated Agriculture Research and Extension Center in Prosser are studying micronutrient utilization in Concord grapes. Washington is the nation’s No. 1 Concord grape producer, so understanding what happens with micronutrients is important to the industry’s bottom line.

And micronutrient availability is an issue in Washington’s grape-growing region, with its high pH soils. The soil availability of micronutrients decreases as pH increases.

“Right now, growers apply micronutrients based on their experience and on what’s commercially available. We want to give them quantifiable data to work with,” said Davenport. “Then they’ll be able to supply plants what they optimally utilize without spending more than they need to on inputs.”

If the vine doesn’t get enough boron, Davenport said, pollen lands on the flower but doesn’t germinate. “That’s a disaster,” she said, “because if there’s no pollination, there’s no seed, and then there’s no fruit.” Copper and zinc don’t affect the plants so dramatically, but do affect the size of the canopy.

Kami Laffey, a recently graduated Prosser High School student who worked with the WSU viticulture and enology program last summer, assists Suphasuk “Bird” Pradubsuck in the excavation of a Concord grape vine.
Kami Laffey, a recently graduated Prosser High School student who worked with the WSU viticulture and enology program last summer, assists Suphasuk “Bird” Pradubsuck in the excavation of a Concord grape vine.

Davenport’s current project is based on one her doctoral student, Suphasuk “Bird” Pradubsuck, finished in 2009.

“Bird excavated Concord vines at various times during the growing season and then did detailed and comprehensive analysis of the plant parts in order to ascertain the amounts per acre of micronutrients the plants used,” Davenport explained.

Macronutrients, such as nitrogen, are measured in pounds per acre, while micronutrients are generally measured in parts per million. “A typical Concord yield is about eight tons per acre,” said Davenport. “To get that, the plants need about 50 pounds of nitrogen per acre, but only a third of a pound of boron.”

Davenport is running extensive field trials on micronutrient utilization with a cooperating grower. “We’re putting on micronutrient fertilizers as both ground and foliar applications,” she said, in order to determine whether vines take up the nutrients from the soil or through their leaves.

Davenport’s research has direct impact on wine-grape growing as well. She and her team are imposing nutrient deficiencies on Cabernet Sauvignon and Semillon grapes.

“All micronutrients have different M.O.’s. By depriving plants of individual nutrients, we’ll be able to see what affects they have and, with the field study data, compare the results in ways that inform wine-grape growers. It’s all about yield and quality,” said Davenport.


Filling the GAP to Potential New Markets

WSDA auditor Chuck Dragoo looks on as Andy Bary reviews the WSU Puyallup Organic Farm GAP food safety procedures manual.
WSDA auditor Chuck Dragoo looks on as Andy Bary reviews the WSU Puyallup Organic Farm GAP food safety procedures manual.

When the Washington State Legislature passed the Local Farms-Healthy Kids Act in 2008, it opened a potential new market for local fruit and vegetable producers. The Washington State Department of Agriculture’s Farm-to-School Program is working to build partnerships to enable local growers to take advantage of not only the local school market but also opportunities to provide produce to other institutions.

According to WSDA Farm-to-School Program coordinator Tricia Sexton Kovacs, one major step that local producers can take toward taking advantage of those markets is to submit their operations to Good Agricultural Practices and Good Handling Practices audits.

“GAP certification isn’t a mandatory part of the program, but some participating schools and distributors are requiring growers to obtain third-party certification,” she said.

To familiarize growers with the audit process, the organic farm at the WSU Puyallup Research and Extension Center on Monday walked through a mock on-farm audit as part of the WSU Small Farms Program and Tilth Producers’ farm walk series.

According to Chuck Dragoo, WSDA fresh fruit and vegetable auditor, the audits are designed to document that a farm has procedures in place to minimize microbial contamination of its crops.

“Usually these food safety procedures are in place and being done, but they are just not properly documented,” Dragoo told the growers. “Documentation is the key for an auditor.”

A simple in-field hand washing station that meets USDA GAP standards.
A simple in-field hand washing station that meets USDA GAP standards.

WSU soil scientist Andy Bary told the group that the best time to start preparing for an audit is in the winter after harvest is completed.

“It takes some time to write up your on-farm procedures and to set up the documentation process,” Bary said.

Bary said he created a three-ring binder notebook for the WSU farm that outlines standard operating procedures and includes the documentation that they are being followed.

“The notebook becomes your on-farm food safety plan,” he said. “It covers such areas as a policy section documenting our standard operating procedures for assuring proper on-farm sanitation, a variety of logs to document that the procedures were followed, and farm employee training records.”

To get started, auditor Dragoo said growers should obtain the U.S. Department of Agriculture Good Agricultural Practices and Good Handling Practices audit checklist which is available at http://bit.ly/bWho3Q.

It lists all of the areas included in an audit and explains the scoring system used in the audit process, although not all sections may be required for every farm.

More information on the WSDA Farm-to-School Program including information about upcoming projects, including WSDA’s Farm-to-Prison pilot project, and how to participate can be found at http://agr.wa.gov/farmtoschool.

WSU Extension will soon be announcing a new series of GAP food safety workshops, thanks to funding from the WSU Western Center for Risk Management Education and the USDA National Institute of Food and Agriculture.


WSU and Organic Agriculture

For over 30 years, Washington State University has been a pioneer in organic agricultural sciences.

WSU was the first university in the nation to offer an undergraduate degree in organic agricultural production.

WSU faculty are worldwide leaders in basic and applied scientific discoveries involving organic systems.

Working with farmers throughout Washington, WSU teaching, research, and extension has helped to make the state one of the largest producers of organic/sustainable agricultural products in the country.

However, we have not compiled the stories behind that work into a single document — until now. Learn more about the exciting and innovative research currently going on at WSU in the field of organic agriculture by visiting http://bit.ly/94gESg.