Horticulture meetings feature record number
of organic presentations

Researchers share findings on production issues, post-harvest management strategies and consumer preferences

By Laura Sayre

September 1, 2005: In another small but significant milestone for organic agriculture, the recent annual meeting of the American Society for Horticultural Science included 50 individual presentations on organic horticulture, with six multi-part sessions devoted entirely to organic topics and a further six organic presentations offered within other topical sessions. The increase reflects a developing recognition among horticultural researchers of the organic sector's commercial importance and of the wide array of potential research questions organic systems present.

One poster session was dedicated entirely to organic production issues. Posters were presented on weed management in organic bell peppers and sweet corn in Kentucky, potato leaf hopper damage in organic potatoes in New Jersey and organic high-tunnel tomato production in Pennsylvania and Maryland, among other topics. Researchers from Ohio State University reported that organic strawberries contained higher levels of antioxidants than conventional strawberries, although antioxidant levels varied more widely by variety than by management system.

Extension researchers in California measured residual soil nitrate in fall cabbage fields receiving supplemental N from seven different organic fertilizers, including feather and blood meals, and found that liquid fish waste resulted in the highest residual soil nitrate levels and the highest marketable yields. Jorge O'Ryan of the Universidad de las Americas in Santiago shared the results of a 2004 survey of Chilean organic vineyards, which currently make up two percent (approaching 2,000 ha, or 5,930 ac) of Chile's total vineyard area and enjoy ideal growing conditions.

A second poster session addressed the relationship between sustainable and organic agriculture and water utilization. Among other presentations, Hector Valenzuela of the University of Hawaii reported that rape cover crops and EM biostimulants increased yields and helped minimize pink root in sweet onions, while Olivia Riffo and Monica Ozores-Hampton showed that food waste compost could be substituted for peat as a potting mix ingredient for some annual ornamental crops in Florida.

From bananas to walnuts

In a session on tropical agriculture, J. Pablo Morales-Payan of the University of Florida outlined the key factors in the success of the organic banana sector in the Dominican Republic, which in 2004 reached 3,200 ha (7,907 ac) and 65 percent of total banana production in that country. In an oral session on pest management, William Coates of the University of California Cooperative Extension reported on an assessment of susceptibility to walnut husk fly among English walnut cultivars, noting that although kaolin and a combination of spinosad plus bait are effective against the pest, cultivars vary in the timing and degree of susceptibility. Kathleen Delate and colleagues at Iowa State University reported on a study of weed management in organic grapes in a poster session on viticulture.

An oral session devoted to organic horticulture featured reports on organic transition strategies for farms on the urban fringe, consumer responses to organic vs. conventional spinach, and the use of surface-banded poultry manure followed by wood chips to fertilize tangelo trees. Using a colorimetric assay for a marker transgene, researchers in Hawaii found that the primary source of GE contamination in organic papaya fields is unwitting use of contaminated seed rather than pollen drift. Other Hawaiian researchers reported that larger, better-quality ginger roots were obtained with organic soil amendments than with synthetic fertilizers. A group in Minnesota determined that transplanting was a viable production strategy for small acreage organic sweet corn, but that vinegar and acetic acid were not workable as organic herbicides for carrots and onions.

Another workshop focused on post-harvest challenges and opportunities for organic agriculture. Researchers from the USDA-ARS station in Fort Pierce, Florida, reported that consumers could readily differentiate between organic and conventional tomatoes by smell or taste. Robert Prange of Agriculture and Agri Food Canada surveyed organic alternatives to control post-harvest decay, noting that controlled atmosphere technologies are the most promising and that continuous ethylene exposure, for instance, has been registered in Canada and the UK as an alternative to the chemical chlorpropham to control potato sprouting.

And from propagation to education

The Plant Propagation Working Group sponsored a workshop on organic vegetative propagation, inviting an open discussion of techniques and research related to the production of organically produced clonal propagules.

Finally, a three-hour session was devoted to the topic of curriculum development for organic horticulture. Researchers and educators from the University of California at Santa Cruz, North Carolina State University, the University of California at Davis, Michigan State University, the University of Florida, Kansas State University, the University of Minnesota, the University of Idaho, Oregon State University and Iowa State University outlined the challenges and successes of a variety of approaches to training and education in organic horticulture, from student organic farms to training sessions for farm apprentices to new undergraduate and graduate courses and programs. Participants described strong student demand for organic training and considerable success is establishing new programs despite downward budgetary pressures on horticulture programs in general.

For more on the 2005 ASHS conference program, visit

Laura Sayre is senior writer for

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