UNIVERSITY PARK, Pa. — In an effort to boost the profitability and sustainability of organic specialty crop productions, a team of scientists is improving and optimizing a method for controlling soilborne pests and pathogens and promoting soil health that prevents oxygen from entering the soil.

Anaerobic soil disinfestation — often referred to as ASD — is the process of limiting oxygen from the soil to reduce pests and pathogens. ASD is important because, in Pennsylvania for example, much of the production of organic specialty crops such as strawberries and vegetables occurs in unheated greenhouse-like structures known as high tunnels. These systems help commercial farmers to extend their growing season and improve the profitability and productivity of their operations. But because soils beneath high tunnels support an intensive cropping system and are shielded from freezing temperatures, undesirable bacterial and fungal pathogens and pests often accumulate in the soil.

Similarly in Florida, high temperatures and humid conditions determine high soilborne pathogens and pest pressure, which limit the expansion of the organic strawberry and vegetable industry.

ASD involves the addition of organic materials to provide a source of carbon that is easily broken down to feed the microbes in the soil and initiate a process that leads to a temporary shift of conditions in the soil from aerobic to anaerobic, explained research team leader Francesco Di Gioia, assistant professor of vegetable crop science, Penn State College of Agricultural Sciences.

Under anaerobic conditions, these materials undergo a sort of fermentation process mediated by microbial activity, which leads to the production of organic acids and other compounds that are toxic to most soilborne pests and pathogens. The system, however, later returns to normal aerobic conditions.

Funded by a $3 million grant from the U.S. Department of Agriculture’s Organic Agriculture Research and Extension Initiative, a large, multi-university research team will develop effective integrated strategies to preserve soil health and enhance the sustainability of organic horticulture using anaerobic soil disinfestation.

“ASD promotes the simultaneous control of plant pathogens, plant-parasitic nematodes and weeds. The goal of this research and extension project is to contribute to the long-term profitability and sustainability of organic specialty crop production systems,” Di Gioia said. “We’ll accomplish this by optimizing and integrating ASD as a viable biological technology for promoting and supporting long-term soil health.”

The four-year project will include coordinated research and on-farm trials aimed at optimizing and integrating ASD into organic vegetable and strawberry cropping systems in Florida and Pennsylvania, two states representative of the U.S. Northeast and Southeast regions. Researchers will assess the impact on soil health and the efficacy in managing targeted soilborne pests and pathogens in the field.

Science-based knowledge developed throughout the project on ASD will be disseminated through local and regional outreach activities such as on-farm trials and demonstrations, farmer focus groups, in-service training, workshops, and public meetings. At the national level, the results of the project will be disseminated through the eOrganic web platform. The project’s webpage will include news and updates, webinars, videos, fact sheets and manuals to instruct the public, both in English and Spanish.

“Collectively, these outreach methods will contribute to knowledge transfer of the ASD technology and application practices to organic growers,” Di Gioia said. “This will help to promote the adoption of sustainable management of soilborne pests and pathogens affecting organic specialty crop systems.”

Other research team leaders are Francisco Dini Andreote, assistant professor of phytobiomes, Penn State; Xin Zhao, professor, Horticultural Sciences Department, University of Florida; and Jason Hong, molecular biologist with the Horticultural Research Lab of the U.S. Department of Agriculture's Agricultural Research Service. The research and extension team includes vegetable and strawberry specialists, soil biochemistry and soil microbiology specialists, plant pathologists, a nematologist, agricultural economists, and extension educators from Penn State Extension and the University of Florida, Institute of Food and Agricultural Sciences.