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  • Author or Editor: Heather M. Darby x
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A major challenge in organic apple production in humid production regions is the available fungicide options for apple scab [Venturia inaequalis (Cooke) Wint.] management. The standard sulfur/lime sulfur fungicide program can be injurious to the applicator, the apple ecosystem, and the apple tree itself. The objectives of this study were to compare the efficacy of three potential alternative fungicides [potassium bicarbonate (PB), neem oil (NO), and Bacillus subtilis (Bs)] with a standard organic sulfur/lime sulfur (SLS) fungicide program and a non-treated control (NTC) for management of apple scab and to evaluate potential non-target impacts on pest and beneficial arthropod populations. The five treatments were applied to ‘Empire’ trees arranged in a completely randomized design with five single-tree replications at the University of Vermont Horticultural Research Center in South Burlington, VT. Fungicides were applied with a handgun to drip using maximum label rates. Applications began on 26 Apr. 2007 and 23 Apr. 2008 and continued on approximately a weekly schedule through the end of June and then every 2 weeks through 23 July 2007 and 17 July 2008, respectively. The standard SLS treatment resulted in the best scab control in both years. The NO treatment reduced foliar and fruit scab compared with the NTC and the other alternatives at the end of the 2008 growing season and had insecticidal activity. However, both the SLS and NO treatments had disadvantages, including phytotoxic burning on the fruit and/or significantly more russeting on the fruit at harvest. In each year of the study, one or more of the alternative treatments, particularly Bs, resulted in higher insect damage than the non-fungicide-treated control. This research showed that PB, Bs, and NO do not offer advantages over the standard SLS fungicide program in organic apple production and in some cases offer distinct disadvantages in terms of non-target impacts. Chemical names used: potassium bicarbonate (Armicarb “O”), Bacillus subtilis (Serenade MAX), neem oil (Trilogy), sulfur (Microthiol Sulfur)/lime sulfur (Miller Lime Sulfur)

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eOrganic is the organic agriculture community of practice (CoP) and resource area for eXtension. eOrganic’s primary community of interest (CoI) is organic farmers and the agricultural professionals who support them. The 250 members of the eOrganic CoP include farmers, researchers, certifiers, and extension/other agricultural professionals. eOrganic’s mission is to build a diverse national CoP and use web technologies to synthesize existing information, emerging science, and practical knowledge into information resources and training materials for its CoI. eOrganic strategies to achieve that mission include collaborative publication, stakeholder engagement, community development, project management, evaluation, and fundraising. eOrganic’s public site currently offers 240 articles, 250 videos, 80 webinars and broadcasts, and 100 frequently asked questions (FAQs). eOrganic CoP members have answered more than 1000 “Ask an Expert” questions. eOrganic authors collaboratively develop articles in eOrganic’s collaborative workspace, which undergo review by two anonymous reviewers and National Organic Program (NOP) compliance review. eOrganic will offer online courses in 2012. eOrganic stakeholders evaluated eOrganic articles and videos in 2010 and overall they stated that they were relevant, science-based, and useful. Three quarters of webinar and broadcast participants said the webinar improved their understanding of the topic, and 83% said they would recommend the webinar to others. Sixty-nine percent of webinar survey respondents stated that they changed practices or provided others with information as the result of the webinar. eOrganic surveyed active CoP members in 2011. Members view eOrganic as important because it is the only national organic agriculture resource with direct ties to university research and they considered all of eOrganic’s core activities important. eOrganic is supported by small grants from eXtension and subawards in more than 20 U.S. Department of Agriculture (USDA), National Institute of Food and Agriculture (NIFA) research/extension projects. To enhance its financial sustainability, eOrganic will work to solidify its partnership with NIFA programs and diversify its funding sources to include course fees and underwriters.

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