Organic Weed Control Method Getting Special Attention

By Penn State News|September 26, 2024

USDA has awarded a four-year, $1 million grant to a research team led by plant scientists from Penn State to investigate anaerobic soil disinfestation, a microbial-driven process to manage weeds, to support transitioning from conventional to organic production systems.

“Anaerobic soil disinfestation — often referred to ASD — is emerging as a broad-spectrum biological soil treatment for the management of soilborne pests and pathogens, including weeds,” says research team leader Francesco Di Gioia, Associate Professor of vegetable crop science in Penn State’s College of Agricultural Sciences. “It is an ecological alternative to chemical soil fumigation. The method consists of incorporating easily decomposable organic amendments into the soil, followed by irrigation to saturation and soil cover with impermeable plastic.”

Soil saturation enhances the decomposition of organic matter, and the anaerobic conditions foster the accumulation of volatile fatty acids and other organic acids in amended soil that are toxic to weeds. The lack of oxygen suppresses weed seed respiration, and those anaerobic conditions result in changes in soil temperature and pH, which work synergistically with other factors to kill weed tissues that could propagate new plants.

The primary goal of this project, according to Di Gioia, is to increase the profitability and sustainability of organic vegetable and other specialty crop production systems and to facilitate the transition from conventional to organic production practices. This can be accomplished, he explained, by optimizing and integrating the use of anaerobic soil disinfestation as a biological weed-management tactic in specialty crops systems, while promoting soil health.

The project will include coordinated research activities, including on-farm demonstration trials to evaluate the efficacy of the tactic in suppressing key weed species in Florida and Pennsylvania, two states representative of the U.S. Northeast and Southeast regions.