Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 2/23/2012
Publication Date: 6/18/2012
Citation: Mazzola, M. 2012. Progress in Brassicaceae seed meal formulation and application for replant disease control in organic apple orchards. Page 9, in, Proceedings 2nd International Organic Fruit Research Symposium. Interpretive Summary:
Technical Abstract: Brassicaceae seed meals when used independently do not provide uniform or sufficient control of the pathogen complex that incites apple replant disease. Trials were established at multiple sites (STM, SR and Tukey orchards) in Washington State to evaluate the efficacy of seed meal formulations for control of this disease in organic production systems. Seed meal applications were conducted in the autumn prior to planting or the spring of planting and tarped with a virtually impermeable film for a period of 7-10 days. Formulations composed of Brassica juncea/Sinapis alba (Bj/Sa) or B. juncea/Brassica napus (Bj/Bn) seed meal significantly improved apple tree growth and suppressed the target pathogen complex at all sites. The Bj/Sa formulation was superior to Bj/Bn in promoting tree growth but spring application of the Bj/Sa formulation to the low organic matter SR orchard soil caused significant phytotoxicity and approximately 40% tree death. At this same site, Bj/Sa seed meal application in the autumn prior to planting resulted in tree growth that was equivalent to that attained in response to pre-plant soil fumigation. Initial year tree growth was improved by Bj/Sa seed meal application at the Tukey orchard, however significant rodent damage and additional unidentified factors resulted in significant tree mortality during year two. At the STM orchard, application of Bj/Sa seed meal in the spring of planting provided superior disease control and tree growth relative to soil fumigation with 1,3-dichloropropene/chloropicrin, and reduced in-row weed coverage by approximately 85% with weed suppression evident at the end of the growing season. These preliminary data indicate that the seed meal formulation may be as or more effective than pre-plant soil fumigation for control of replant disease, but that plant back periods and seasonal application requirements will vary with soil type.