Proliferation of morning glory (Ipomoea spp.) in soybean (Glycine max) fields in Japan has become a significant concern, and it is crucial to establish an effective method to reduce the number of its buried seeds. Therefore, this study was conducted to determine the effects of different field management practices on the number of germinating and buried seeds of Ipomoea coccinea (red morning glory) that infested a soybean field. Field experiments were conducted in the same soybean field from 2017 to 2019, and no new buried seeds were produced by weeding throughout the experimental period. The cumulative number of I. coccinea seedlings during the soybean cultivation season decreased year by year, with a 63–64% decrease observed in the second year and 8–20% in the third year than in the first year of cultivation. This suggests that exhaustive control of I. coccinea and prevention of its seed production will make weed management much easier in the future. The number of buried seeds tended to be higher in the “no-tillage” plot than in the “tillage” plot, which showed the presence of up to 70% of seeds after three years. Conversely, regular monthly tillage from spring to fall decreased the number of buried seeds to 22–25% after three years. This indicates that regular tillage can efficiently reduce the number of buried seeds of I. coccinea, regardless of whether soybean is cultivated.

Lawn burweed (Soliva sessilis Ruiz & Pav.), an annual weed native to South America, has sharp achene spines that prevent the use of lawns. It is difficult to control lawn burweed by mowing because of its creeping growth form. We conducted field experiments to assess the effects of foliar applications of hot water as a lawn burweed control. In mid-April, a pressure washer was used to apply hot water (98°C) to plants in a park in Tokyo, Japan. Individual plants were spot treated with 304–1,824 mL of hot water per plant (treatment time 2–12 sec); all died by 28 days after the treatment. Surface treatment of a 1 m × 1 m-plant community comprising 10–20% lawn burweed with 760, 1,520, or 2,280 mL/m² of hot water for 5, 10, or 15 sec, reduced the lawn burweed coverage to less than 8%. However, the 760-mL/m² treatment sometimes resulted in uneven spraying of tall plant communities, so a minimum of 1,520–2,280 mL/m² should be used.