Integrated weed management (IWM) for agronomic and vegetable productionsystems utilizes all available options to effectively manage weeds.Late-season weed control measures are often needed to improve crop harvestand stop additions to the weed seed bank. Eliminating the production ofviable weed seeds is one of the key IWM practices. The objective of thisresearch was to determine how termination method and timing influence viableweed seed production of late-season weed infestations. Research wasconducted in Delaware, Michigan, and New York over a 2-yr period. The weedsstudied included: common lambsquarters, common ragweed, giant foxtail,jimsonweed, and velvetleaf. Three termination methods were imposed: cuttingat the plant base (simulating hand hoeing), chopping (simulating mowing),and applying glyphosate. The three termination timings were flowering,immature seeds present, and mature seeds present. Following termination,plants were stored in the field in mesh bags until mid-Fall when seeds werecounted and tested for viability. Termination timing influenced viable seeddevelopment; however, termination method did not. Common ragweed and giantfoxtail produced viable seeds when terminated at the time of flowering. Allspecies produced some viable seed when immature seeds were present at thetime of termination. The time of viable seed formation varied based onspecies and site-year, ranging from plants terminated the day of floweringto 1,337 growing degree d after flowering (base 10, 0 to 57 calendar d).Viable seed production was reduced by 64 to 100% when common lambsquarters,giant foxtail, jimsonweed, and velvetleaf were terminated with immatureseeds present, compared to when plants were terminated with some matureseeds present. Our results suggest that terminating common lambsquarters,common ragweed, and giant foxtail prior to flowering, and velvetleaf andjimsonweed less than 2 and 3 wk after flowering, respectively, greatlyreduces weed seed bank inputs.