EVALUATING DISEASE PREVENTION METHODS FOR ORGANIC AMERICAN GINSENG PRODUCTION IN APPALACHIA, AN INTEGRATED RESEARCH, EDUCATION, AND EXTENSION APPROACH

The four pillars in the sustainable agricultural system are commonly considered as production efficiency, economic dynamics, ecological impacts, and social responsibility. Our ultimate goal of this project is to develop scientific solutions for and to promote sustainable organic AG production in Appalachia using an integrated research, education, and extension approach (Fig. 1). A four-stage research effort will be conducted sequentially in laboratory, the green house, small-plot organic lands; and producer sites. All four research stages will be integrated with education and extension components. This multipronged system approach will help addressing key managerial issues challenging organic AG production and help increase biodiversity both above and below ground resulting in a more resilient ecosystem while attenuating fungal pathogen pressure and lessening the replant issue. This approach may be easily adapted by regionally divergent farms by adjusting selected bacterial endophyte and cover crop species. Specifically, we have five objectives of this program.Objective 1: Evaluate the effectiveness of biological control microbial antagonists on fungal disease prevention and treatment for organic AG production.The use of biological control agents to both suppress pathogen presence and promote growth in organic agriculture is well documented (O'Callaghan, 2016). However, few studies have demonstrated their effectiveness on ginseng production. Many of these studies were carried out using P. ginseng. Some bacterial antagonists are already on the market for control of Pythium; Companion (B. subtilis), Primastop (Gliocladium caterulatum), Actinovate (Steptomyces lydicus), Mycostop (Steptomyces griseovirdis), PlantShield (Trichderma harzanum), and SoilGard (Trichoderma virens) are all marketed for use against Botrytis, Fusarium, Phytophthora, and Rhizoctonia (Moorman, 2011). These products however, do not specifically mention their use or efficacy on AG (P. quinquefolius). Here we seek to fill in gaps in our collective knowledge of how the use of biological agents will protect AG production.Fungal pathogens tend have a limited range of host species that they harm, often refereed to has host specificity (Li, Cornelissen, & Rep, 2020). Because of this circumstance, the fungal pathogens effecting AG will be collected and identified from wild environments, collaborating ginseng growers and academic researchers. Meanwhile, bacterial endophytes from regional AG genotypes will also be collected, screened against the isolated pathogens, and identified. The effect of the bacterial antagonists on the growth of AG plant and plant resistance to fungal disease will be investigated. In addition, because phytochemical content is one of the key factors determine ginseng's value and it has been reported that bacterial antagonist could increase the phytochemical contents, the phytochemical accumulation after bacterial inoculation will also be investigated.Objective 2: Evaluate the effect of biological control microbial antagonists on soil physiochemical and biological conditions.Soil-borne ginseng fungal pathogens alter the soil microbiome by reducing the species and growth of beneficial bacteria. Our hypothesis is that by introducing or increasing native bacterial species known to be antagonist to fungal pathogens, we can restore the bacterial diversity and population size of antagonistic bacteria that were altered by the fungal pathogen or continuous ginseng production. Our approach will be to assess bacterial diversity and population size in the rhizospheric soil of healthy anddiseased AG. Metabarcode analysis will be used to survey prokaryotic and fungal taxa associated with healthy and diseased AG plants. If specific taxa are found to be associated with healthy AG plants it may be possible to identify those taxa and introduce them into the soils as part of an organic cultivation strategy. These results will allow us to quantify bacterial population and diversity reductions in soil involved in AG production and offer an important baseline number. Bacterial strains shown to be antimicrobial will then be reintroduced into ginseng production fields at levels at or above our baseline finding.Objective 3: Evaluation of the antifungal effect of natural botanical extracts against AG's fungal pathogens.The severity of ginseng replant disease appears linked to the production environment. While replant failure is common in cultivated AG production, it is much less common in forest farmed AG cropping systems. However, fungal disease tends to increase with increasing intensification of forest farming practices. Wild populations of AG contain assemblages of associated plant species, and growers evaluating sites for wild-simulated plantings use these associated plants as 'indicator species' in determining suitability for AG reintroduction. Some of these indicator plant species (i.e. Adiantum pedatum, Arisaema triphyllum, Botrychium virginianum, Caulophyllum thalictroides, and Podophyllum peltatum, Polygonatum biflorum), as well as some woodland companion crops sometimes interplanted with AG (i.e. Allium tricoccum, Cimicifuga racemosa, Hydrastis canadensis), are reported to possess anti-fungal properties. We hypothesize that these plant associates contribute to the reduced disease incidence found in wild or wild-simulated AG populations through antifungal root exudates or compounds in decomposing leaf litter. To test this hypothesis, we will evaluate the antifungal potential of ethanol and aqueous extracts made from select indicator species and companion crops with the goal of developing simple DIY anti-fungal soil treatments that will be shared with growers through our outreach efforts. We will identify these select candidates for study using grower experience coupled with our knowledge of associated flora and possible novel antifungal chemistry associated with a particular species.Objective 4: Promote sustainable organic production and certification to local, regional and national ginseng producers by emphasizing both the consumer's market preference and higher price yield the anticipated research solutions will deliver.The authentication of herbal products through organic certification provides confidence and quality assurances to consumers who are willing to pay for the price premium of certified ginseng products that involve no chemical inputs. Two current examples are the 'Grown in Wisconsin' Seal - simple geographic certification that has increased demand and relative market price (Ginseng Board of Wisconsin 2021); and in Asia, the Chinese "Green Food Certificate" (a partial equivalent to our USDA organic certification) also drives both demand and price for organic products (Liu et al., 2021; China Green Food Development Center). We will develop a market analysis for the cost/return of AG organic transitioning and production and design training models that will help AG producers to become certified. Our outreach will include a training component for ginseng producers by promoting sustainable organic management techniques and certification and on how to niche-market their product at higher prices.Objective 5: Disseminate and transfer the project results to stakeholders and public individuals.Results and best practices identified through this work will be made available through various educational and outreach efforts conducted by project team members and collaborators in various Appalachian states (TN, PA, OH, VA, NC, KY, and NY). An educational component includes teaching activities at MTSU, University of Tennessee, UVA-Wise, and Penn State University and undergraduate research activities in these institutions will be developed.