Weed Management by In Situ Cover Crops and Anaerobic Soil Disinfestation in Plasticulture

Weeds negatively affect organic vegetable crop growth and profitability. Weed management is the greatest challenge for vegetable organic growers since control options are limited for organic vegetable production. Anaerobic soil disinfestation (ASD) is a novel non-chemical pest management technique that creates anoxic conditions in the topsoil layer for a limited time. ASD is primarily based on the addition of labile carbon sources to topsoil to promote anaerobic conditions driven by microorganisms in moist soil mulched with polyethylene film (polyfim). Field studies were conducted in the summer-fall of 2020 and 2021 to determine the efficacy of warm season cover crops used as carbon sources for ASD and their role in weed management. The study used a factorial experimental design with four cover crop residue treatments (sorghum-sudangrass, sunn hemp, both, or none) in two soil aeration conditions (aerated or non-aerated). Cover crops were grown for 75 days, incorporated into the soil, and sealed with totally impermeable film (TIF) clear mulch, followed by a 4-week ASD process. All incorporated cover crop treatments in non-aerated conditions generated moderate to higher anaerobic conditions (0-150 mV) and provided significantly higher (p < 0.05) weed control than all the other treatments tested or controls. Tomato plants transplanted in non-aerated, cover crops incorporated plots were more vigorous and produced higher yields than aerated plots. No phytotoxicity was observed on tomato plants following ASD treatment in any of the treatments tested. This study demonstrated that warm season cover crops could potentially serve as a carbon source for ASD in organic tomato production.