Strip-tillage (ST) and cover crops can protect and improve soils in vegetable production systems but their effects on weed communities and weed management are often poorly understood. The objectives of this study were to 1) determine the effects of tillage and cover crops on weed seed persistence and emergence, 2) evaluate the extent to which these effects were mediated by fungal pathogens, changes in herbicide efficacy, and light or oxygen exposure, and 3) investigate potential relationships between seed persistence and indicators of microbial activity. Seed persistence and emergence of Powell amaranth and large crabgrass were evaluated in long-term field trials with tillage (ST vs. full-width tillage [FWT]) and cover crop (no cover, rye, and vetch) treatments. Persistence of both species was higher under ST compared to FWT and could largely be explained by lower light exposure in ST. Rye cover cropping resulted in greater persistence of crabgrass seeds, but this could not be explained by fungal pathogens. Soil enzyme indicators of microbial activity including β-glucosidase, leucine aminopeptidase, and acid phosphatase were often higher under ST and rye cover crops and positively correlated with seed persistence. Results suggest that tillage and cover crop effects on emergence are variable due to complex interactions between herbicides, soil moisture, and nitrogen dynamics, all of which impact germination.
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