The five-year project is part of an effort funded by the U.S. Department of Agriculture to improve scientific knowledge about organic systems and to strengthen the Central Coast network of organic farmers and agricultural researchers . Dan Schmida of Sandpiper Farms is the study’s grower cooperator. Other UCSC researchers involved in the project include Center director Carol Shennan, Environmental Studies professor Steve Gliessman, and specialist Sean Swezey, along with Steve Koike, plant pathologist with UC Cooperative Extension. The researchers are testing the effects of several ecological farming practices, including suppressing disease with “biofumigation,” an alternative to fumigation with synthetic chemicals such as methyl bromide. Broccoli residues and mustard crops are incorporated into the soil priorto vegetable and strawberry plantings. As the broccoli and mustard break down they release naturally occurring chemicals thought to reduce the levels of soilborne diseases such as Verticillium dahliae, large round garden pots which causes wilt in strawberries. Other practices include rotating strawberries with broccoli and spinach crops, which do not host Verticillium; using strawberry cultivars less susceptible to disease; and incorporating compost to enhance biological activity and increase levels of organic matter.
Learning to manage nutrients efficiently is another of the project’s goals. “Strawberries are a tricky plant—they need nitrogen at the right time and in the right amount,” says Muramoto. “We’re looking at the best ways to adjust fertilizer and compost levels and application timing in order to meet crop demands throughout the season while decreasing the loss of nitrogen from the system.” Nitrogen that leaches into groundwater or runs off the fields can pollute adjacent waterways—including the ecologically sensitive Elkhorn Slough—and cost growers money in the form of lost resources. “The weather pattern here on the Central Coast makes nutrient management challenging,” says Muramoto. Most of the season’s rainfall occurs from late November through April, when the shallow root systems of strawberry plants are not fully developed. Although applying a plastic mulch over the beds prior to heavy rains helped decrease the loss of nitrogen from the system, there was still a significant level of nitrogen in storm runoff from the fields following the season’s first rains. “We found that surface runoff, rather than leaching, is the main way that nitrogen is carried out of the fields,” says Muramoto. “If there is a high level of inorganic nitrogen in the soil when the first heavy rains hit, a significant portion of that nitrogen can be lost.” Muramoto notes that growers should work to reduce the basal nitrogen level in the soil by minimizing pre-plant compost applications, especially if a broccoli residue has been incorporated prior to planting the strawberry crop. “Growers can take advantage of the nitrogen that the broccoli residue provides and save money by reducing the use of other inputs,” he says.
Monitoring for Verticillium dahliae has shown that incorporating broccoli residue prior to planting strawberries consistently reduced the numbers of Verticillium propagules in the soil. In contrast, incorporating mustard did not reduce Verticillium numbers. Although it was thought that the chemicals released by both broccoli and mustard should supress Verticillium populations, studies suggest that another factor may be at work. “Broccoli residues may increase the population of bacteria that break down both broccoli and Verticillium, which have similar cellular structures [chitin], whereas mustard may not stimulate populations of these bacteria,” says Muramoto. Despite the fact that the mustard did not lower the populations of Verticillium, no wilting effect was seen in the strawberry crop. According to Muramoto, other researchers suggest that mustard residues may stimulate competition among microbes for entry points into the strawberry roots, thus blocking some of Verticillium’s ability to infest the crop. However, Muramoto noted that it’s difficult to tease out the specific effects of mustard and broccoli in this study since the crops are planted in sequence. In addition, Muramoto learned that Capsella bursa-pastoris, or shepherd’s purse, a common weed in the region, also hosts the Verticillum dahliae fungus and can increase its presence in the soil. Based on this finding, plant pathologist Steve Koike suggests that weed management should be integrated with soil-borne disease management. The research will continue for another season, during which all of the fields will be planted with strawberries. “This fifth year of the study will tell us the most about the various rotations’ effect on strawberry production and plant health,” says Muramoto.Controlling soil-borne diseases without synthetic chemical fumigants such as methyl bromide is one of the biggest challenges facing organic growers. This is particularly true for organic strawberry growers, whose delicate crop is subject to a range of soil-borne fungal diseases.
Verticillium wilt, caused by the fungus Verticillium dahliae, canbe particularly vexing—growers are often forced to find “clean” ground every year in order to avoid planting strawberries into areas where levels of Verticillium have built up over time. As housing and other development projects eat away at the amount of available farmland in areas such as California’s Central Coast region, finding new ground is becoming more difficult. One promising technique for controlling a number of plant pathogens across a range of crops comes from the Netherlands and Japan. The technique involves growing and incorporating a cover crop, watering the area, and then sealing it with an oxygen-impermeable tarp to create anaerobic conditions that kill the fungal pathogens. Japanese use wheat bran in place of a cover crop for a carbon source. In the summer of 2004, Center director Carol Shennan, researcher Joji Muramoto, and UCSC Farm manager Jim Leap conducted a trial of the anaerobic residue digestion technique in a field that had experienced an outbreak of Verticillium wilt and Phytophthora root rot in strawberries. The average population of Verticillium dahliae in the plot’s topsoil was 3 micro-sclerotias per gram soil; only 1 micro-sclerotia per gram of soil is needed to cause Verticillium wilt in strawberry plants. The randomized, complete block design compared two types of cover crops , with or without tarping. The cover crops were incorporated on July 13, 2004; following incorporation, a soil sample densely infested by V. dahliae was buried as an inoculant in each plot. Leap then applied 50 millimeters of water to the plots overnight; a plastic tarp was applied on July 14 and kept in place for 12 weeks, during which Eh and temperature were measured in the plots. Regardless of cover crop type, large round pots the number of V. dahliae microsclerotia in recovered inoculants decreased to 0.3 per gram in the tarped plots , while the number in the non-tarped plots increased to an average of 23 per gram. Eh levels indicated that weak anaerobic condition developed during the first two weeks of tarping. On November 18, 2004, strawberries were planted in all plots. Disease symptom of strawberry plants, V. dahliae population in the soil, and strawberry fruit yield are being monitored through the growing season, with initial findings showing a lower level of Verticillium wilt symptoms in the tarped plots. Based on the encouraging results from the 2004 study, a new tarping trial was initiated this summer at the UCSC Farm. The researchers are comparing tarping periods of 3, 6, and 12 weeks. The study will also compare covering the plots with clear versus black tarps to see whether differences in temperature affect levels of V. dahliae. The plots will be planted with strawberries in the fall of 2005.A new greenhouse, a national conference on sustainable agriculture education, scholarships for apprentices, a farm to-cafeteria project, and a stock-free demonstration field project at the UCSC Farm—these are a few of the things that new grants and gifts will help fund in the coming year. Along with key funding for the Apprenticeship training program, a total of $135,000 has been raised so far for 2006 education-related projects.
We are grateful to the following funders for their support – The True North Foundation has granted $30,000 for the new Farm to Cafeteria project along with the continuation of the Community Supported Agriculture Education and Outreach program. The new funding will allow Apprenticeship staff to work with the Campus Food Systems group at UC Santa Cruz to bring organic produce to the campus cafeterias and restaurant while doing outreach and education on campus about sustainable agriculture and local food systems. A $25,000 grant from the AT&T Pebble Beach Charities will go toward the construction of a new educational greenhouse at the UCSC Farm. We are grateful for this grant brought in with the help of the Monterey Peninsula Foundation, which will help us leverage further funding for the new greenhouse. Newman’s Own Organics, with a $30,000 grant, and Nan McEvoy, with a $5,000 gift, have provided ever-important core support for the Farm & Garden Apprenticeship training in organic farming and gardening. A new grant of $5,000 from the Foundation for Sustainability and Innovation will allow Apprenticeship staff to do more extensive outreach and recruitment than ever, with a goal of increasing the number and the diversity of applicants to the six-month Apprenticeship training program. An anonymous donor gifted $25,000 to create the “Wild- flower Fund” for Apprenticeship scholarships, a fund that could support as many as seven apprentices over the next seasons of the Apprenticeship course. A new demonstration field at the UCSC Farm will be managed without any inputs from animal sources, thanks to a $4,000 grant from the Nalith Foundation. This “Stock-free” or vegan organic farming demonstration site will provide information on cover crop and plant-based composts as alternatives to animal manures and other animal products such as blood meal and bonemeal.Farm Foundation has pledged $10,000 for the coordination of the first-ever National Sustainable Agriculture Educator’s Conference being planned for January 2006 . This conference will bring together instructors from colleges, universities, and other educational organizations and will be put on in conjunction with the Ecological Farming Conference at Asilomar, California, on January 24–25 . The California Agriculture Teachers Association and the Kellogg Foundation, through the California Food, Fibers, and Futures project, granted $3,000 each to make possible the creation of a sustainable agriculture course curriculum for the community college level as well as a one day agriculture teachers’ in-service training hosted by the Center in June. Program organizer Albie Miles, the Center’s curriculum specialist, noted that colleges throughout the state are developing sustainable or organic agriculture courses at their institutions. The in-service training program for college and university instructors focused on the way that innovative production and marketing strategies used in organic agriculture are influencing the way that food and fiber are produced and sold.The Center recently produced the sixth title in its Research Briefs series. Participatory Action Research and Support for Community Development and Conservation: Examples from Shade Coffee Landscapes in Nicaragua and El Salvador describes a form of research that links both social and ecological questions while generating information that can be used to foster environmental and social change. Based on their experiences conducting research in coffee-growing areas of El Salvador and Nicaragua, Ernesto Mendez and Chris Bacon report and reflect on the opportunities and challenges involved in conducting participatory action research . Both Mendez and Bacon recently completed their doctoral work in Environmental Studies at UC Santa Cruz. The Research Brief uses examples from Mendez and Bacon’s studies in Tecuba, El Salvador, and Matagalpa, Nicaragua to illustrate the process of PAR. Like many coffee-growing communities, coffee growers in these areas are suffering severe economic hardships due to steep declines in coffee prices. Mendez’s work in El Salvador originally focused on biodiversity conservation and farmer livelihoods on shade coffee farms. As the coffee crisis deepened, his “action research” grew to include action-oriented activities such as farmer trainings in organic growing techniques, development of alternative markets, and diversification on the farm. Bacon’s experience in Nicaragua includes work with coffee cooperatives tied to the Fair Trade movement. His dissertation focused on the livelihoods of households linked to cooperatives selling into different coffee trade networks. Among the myriad requirements for successful rose growing is picking the “right” spot in the garden. By and large, roses require a minimum of 6–8 hours a day of full sun during the growing season . This intriguing class of roses, developed in the early 20th century, is capable of growing and blooming prolifically in moderate shade .