We revealed that earlier harvesting of corn grain with high moisture content, using a Japanese combine harvester equipped with a corn header, might reduce the risks of mycotoxin contamination and decreased yield. On the other hand, high moisture harvesting involved higher costs, mainly attributed to prolonged machine-drying time. Furthermore, cleaning of the inside of the combine after each harvesting operation was necessary due to the buildup of moist foliage. These results suggest that high moisture harvesting of corn grain is not realistic in farming.