Anaerobic Soil Disinfestation as a Non-chemical Management Option Against Fungi and Heterotrophic Bacteria in Organic Sweetpotato Production

North Carolina is the largest producer of sweetpotatoes in the United States, with South Carolina increasing farming acreage to 2,501 in 2022 compared to 1,300 in 2017. Growers producing conventional and organic sweetpotatoes are equally challenged with managing fungal pathogens due to fungicide resistance or fungicides being unavailable due to environmental regulations, leading many to shift to growing organic crops. Anaerobic soil disinfestation (ASD) is a non-chemical pre-plant management option that uses a carbon amendment, irrigation, and plasticulture to establish an anaerobic environment in soils, killing soil microbes. A greenhouse study was conducted to assess ASD on fungal pathogens and heterotrophic bacteria in organic soils. This study tested an antimicrobial protocol using a combination of cotton seed meal, black plasticulture, and irrigation to create an ASD system for organic farmers to utilize. Soils from four organic farms in and around Charleston, South Carolina were tested. Soil samples were taken before and after ASD treatment (3 weeks), heterotrophic bacteria and fungi were quantified, and fungal colonies were subcultured to create pure cultures. The pure cultures were identified using DNA barcoding. Data show ASD decreased bacterial and fungal abundance specific to location. Fungal diversity was recorded and similarities among locations are reported. The results of this research provide information towards the goal of creating an effective organic farming application that could promote healthy soils, significantly decrease fungal pathogens, and provide insight on what fungi are present at these locations.