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WSU Mount Vernon Team Studies Damping-Off Management in Organic Vegetables
Large-scale Pacific Northwest organic vegetable producers routinely plant 30 percent more seed than they really want. They do this to help with weed control and because they anticipate losing that much to a plant disease called damping-off, according to Lindsey du Toit, associate professor and vegetable seed pathologist at the WSU Northwestern Washington Research and Extension Center in Mount Vernon. In the worst cases, when a combination of early planting in late February to early March and a cool, wet spring create conditions perfect for damping-off, growers have had to replant entire fields. Paying for that extra seed–anywhere from $20 to $55 more per acre for certain crops–is expensive.
“If they could get this disease under control, then that’s one cost that could be avoided,” said du Toit. She and graduate student Ana Vida Alcala are continuing work from an earlier study to help organic vegetable growers in the Pacific Northwest’s coastal region and central Washington’s Columbia Basin find ways to manage damping-off, also known as seedling blight.
Organic vegetable growers face unique challenges from the get-go. For one thing, they cannot use the same chemicals that conventional growers use to combat the various soil-borne pathogens (Pythium, Rhizoctonia, or Fusarium) responsible for the disease. For another, farmers growing vegetables for the organic processed food market must plant early for several reasons: planting early reduces competition with weeds that are difficult to control with organic methods; to ensure harvest before conventional crops and thus avoid the effort and cost of cleaning the processing facility, which they must do to keep organic certification; and to plant two different crops in one growing season consecutively, thus maximizing return on the farmer’s investment.
Unfortunately, the low soil temperatures and high soil moisture associated with early spring planting allows pathogens that cause damping-off to thrive. The young seedlings are also at their most vulnerable to these pathogens, which are attracted to tender, succulent roots. Damping-off affects the plant’s ability to absorb nutrients and moisture from the soil, resulting in poor emergence and plant growth.
Alcala, who is working toward her doctorate in plant pathology, said she and du Toit are investigating alternative management methods applicable to organic vegetable production, specifically for peas. One method is treating seed with products allowed on certified-organic farms. Seeds treated with NORDOX®, a copper-based fungicide, appeared to grow well in one of Alcala’s field trials that was severely affected by damping-off.
“There are promising results, but we just looked at one season,” Alcala said. “It’s still too early to say for sure. We still have a year and half of my program to fine-tune the information we’re obtaining. We need to study the whole cropping system to ultimately know if organic producers are likely to use these applications.”
Another method that will require further investigation is studying electrolyte leakage from seeds as a tool for predicting damping-off risk in the field, Alcala said. Electrolyte leakage is the loss of dissolved minerals and other nutrients as seeds take up water from the soil. Electrolytes attract damping-off pathogens. Seeds stored for a long time are especially prone to leakage and older or more damaged seeds leak electrolytes faster once they are planted. Pacific Northwest growers found that planting high-quality seeds for organic vegetable crops is very important to ensure good growth and to minimize crop loss.
“If you use poor-quality seed and the pathogen is present in the soil, the chances of the plant becoming infected are higher. You’re making it more favorable for the pathogen,” Alcala said. “So if you have the right soil and weather conditions and poor-quality seed, it really is the perfect storm for damping-off to occur.
The study originally started in 2006 when du Toit and a former graduate student, Jaime Cummings, evaluated seed and drench treatments for damping-off in spinach that were either approved or being developed for certified-organic production. The treatments were tested on Pythium ultimum, Rhizoctonia solani, and Fusarium oxysporum under greenhouse and field conditions.
Alcala took over Cummings’ work in 2009 when du Toit received additional funding to continue the project. They interviewed nine Washington growers of certified-organic vegetables to understand their damping-off management needs. The growers they interviewed work with diverse production systems that range from a few acres of organic vegetable crops to a 6,000-acre certified-organic operation.
Yet the interviewed growers indicated they don’t typically use organic seed treatments because of inconsistent results. Alcala and du Toit are testing different microbial and non-microbial treatments under the same conditions their interviewees encounter. The production processes that Pacific Northwest organic vegetable farmers use may not work with a particular treatment, and some products may do better in warmer soil conditions, rather than in the cool, early spring conditions of central Washington. Still, growers want an effective solution to their damping-off problems.
“Some growers indicated they would pay up to $100, even $150, per acre for a seed or drench treatment that works consistently to significantly control damping-off under their production practices,” du Toit said. “That tells you that this is significant.”
Towards a Sustainability Index for Agriculture
Green Times asked WSU Extension educator and Center for Sustaining Agriculture and Natural Resources team member David Granatstein to define “sustainable.” Granatstein argues that the word has a range of meanings, none particularly helpful when trying to compare one type of farm with another. Rather, he says, what we need is a sustainability index to help us compare different types of farms. Read Granatstein’s essay on the Green Times blog »
What do you think? Post your comments on the Green Times blog or, if you’re interested in presenting your own views at length, write the editor (firstname.lastname@example.org) with your proposal.
Fight the Wilts with Vegetable Grafting
Verticillium wilt is a nationwide scourge, and with the impending phase-out of methyl bromide fumigation, Pacific Northwest growers need new techniques to fight this crop-busting fungus. One new technique comes in the form of a centuries-old Asian practice: vegetable grafting. A team lead by Carol Miles at the WSU Northwestern Washington Research and Extension Center in Mount Vernon is helping watermelon, eggplant, and tomato growers fight the wilts with a time-tested technique modernized for today’s growers.
While some plants, such as bottle gourd, are not economically significant in their own right, growers admire their resistance to verticillium wilt. Miles found that this desirable resistance could be transferred to watermelon plants by grafting watermelon scion (a twig containing the buds that later become a fruit or vegetable) onto bottle gourd rootstock.
“Vegetable grafting,” said Miles, “is a simple, biological method for achieving disease resistance.” Miles and her colleagues have created a web page with publications, animated presentations, and additional resources to guide growers in the use of this method.
Learn more at http://bit.ly/veggraft.
Potato Farmers Reap Many Benefits to the Soil by Using Green Manures
The hazardous weather outlook for the day warned of high winds, possibly gusting up to 40-50 m.p.h. While the National Weather Service warned about damage to trees and buildings, WSU Extension educator Andy McGuire could see another kind of damage. “I sure saw the soil blowing off some fields today,” said the member of the leadership team for WSU’s Center for Sustaining Agriculture and Natural Resources. He called from his hotel in Sunnyside, after a day of fieldwork
Wind erosion, McGuire explained, robs cropland of its tiny, fertile soil particles, while lowering air quality and even causing highway collisions due to reduced visibility. These problems can all be redressed through practices that can build soil quality.
Soil quality is often the answer to many problems, as McGuire discovered when he advised farmers to use green manures, including mustard, sudangrass, and arugula, to control soil-borne pathogens such as verticillium wilt in potatoes. As measured by an increase in organic matter, farmers noticed an improvement in soil quality, and green manures also helped control the fungal organisms that threatened crops,.
Soil with more organic matter has better water infiltration and tilth, or texture. When tilth is better, harvest is faster, soil falls off the potatoes more easily, and the soil is more resistant to compaction. Compacted soils have less pore space for air and water and can decrease plant health and yields.
Conventional agriculture has not always focused on soil quality. Columbia Basin potato farmers were able to achieve high yields through irrigation and fertilizer alone. Without improving the soil, however, wind erosion and intensive tillage can gradually degrade the farmland that potato growers depend on. But green manure, said McGuire, “has the potential to bump up organic matter levels,” reducing wind erosion and improving tilth.
It sounds good, but are farmers convinced? “Green manure acreage is going up every year,” McGuire stated. “We started with 1,500 acres in 1999, and in 2011, it was over 30,000 acres.” The majority of potato farmers using green manures report better soil tilth, more organic matter in the soil, a reduction in wind erosion, improved water infiltration, and better control of verticillium wilt.
Learn more about using green manures by checking out these publications available from WSU Extension: http://bit.ly/wsugrnmanure.
Collaboration Fuels Tribal Biodiesel Project
WSU canola research in collaboration with the Colville Confederate Tribes has enhanced both the region’s economy and environment. This spring, the CCT and area growers intend to build a new canola oilseed crushing facility at the Paschal Sherman Indian School in Omak. The tribe already has a canola storage site in place, said Frank Young, a research agronomist and weed scientist for the USDA-Agricultural Research Service and a WSU adjunct faculty member
Canola is providing the CCT with valuable products such as biodiesel and livestock feed in place of other local resources that are no longer economically viable. “There’s no demand for lumber anymore,” Young said. The market for wood products has decreased and left many tribal members without jobs. The tribe has established a goal to process enough oilseed for biodiesel to fuel the Pascal Sherman school buses and other vehicles, he said.
Meanwhile, a feed store in Okanogan has agreed to distribute crushed canola, in the form of canola meal, to local livestock growers, said Young. Okanogan County has the highest livestock population in the state. The canola meal also will be distributed to local fish hatcheries to feed salmon.
“If you keep one dollar in the local economy, it circulates three times,” Young said.
The next step in the ongoing project is to teach the tribe how to grow canola on abandoned crop land, Young said. Restoring pastures and hay fields could potentially provide 20,000 additional acres of the oilseed crop. The project began with hand-planted and -watered spring canola, but researchers are now focusing their efforts on winter canola, which yields almost twice as much with similar inputs, he said. Used in crop rotation, canola also helps to improve winter wheat yields and weed control.
Reduced tillage and improved water quality are additional benefits from the canola research. “In 2006, the first salmon in 70 years swam up Omak Creek,” said WSU crop scientist Dennis Roe. This was mostly a result of improved conservation practices. Reducing tillage preserves more crop stubble, he said, which will help prevent erosion into the Omak and Foster creeks. Otherwise, eroded sediment fills in the stream channels and smothers fish spawning beds.
The research will look into how to establish canola without excessively disrupting the soil, Roe said. The project also will also work with the tribe to use safer herbicides, reduce the amount used and use other methods to slow the progression of resistant weeds, Young said.
–Tallie Mattson, WSU News intern
Watch “From Field to Fuel,” a short video describing the canola-to-diesel project, by visiting http://youtu.be/Az1sKyOcD3I.
Long Beach Farmers Seek to Be Washington’s First Organic Cranberry Producers
Jared Oakes and Jessika Tantisook are partners in Starvation Alley Farms. The partners are organic farmers pioneering the production of organic cranberry production in western Washington. As they transition to organic production, they are documenting the methods they use so that others may learn from them. And as they transition, they are being mentored by WSU Extension educator Kim Patten, a cranberry expert based in Long Beach, Washington.
Oakes and Tantisook have long been interested in food. With their background in the food and wine industry, they are passionate about being able to work with produce that is grown sustainably and locally. “Food,” said Oakes, “is a microcosm of what happens in the rest of the world. We’ve become enamored of the local food movement and wanted to contribute.”
Oakes said he and his partner are “coming at it form an outside perspective” — they are new to the business of farming but say they are encouraged by the market for their cranberries, by the science-based advice they get from WSU Extension and other sources, and by the ideal of producing healthy, locally grown food.
March 15: Northwest Washington Farm to Table Trade Meeting for Whatcom, Skagit, Island, and San Juan farmers, fishers, ranchers, chefs, distributors, restaurateurs, processors, caterers, and grocers. $15; 9 a.m. – 3:30 p.m. at the Community Health Education Center in Bellingham. Learn more »
March 24: Hard cider making and orcharding workshop. Presented by WSU Snohomish County Extension at Ed’s Apples in Sultan. Learn more »
April 3: Native Pollinators on the Palouse Workshop. 6:30 – 9 p.m. at the 1912 Center in Moscow, Idaho. Learn how to design native-plant landscapes that attract native polinators; where to get native plants. Watch for more information coming soon on the Green Times blog, or contact Brenda Erhardt at 208-882-4960.
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