To effectively restore farmlands abandoned for years, the performance of three flail mowers used for removing woody plants was evaluated. The three selected mowers were mounted on tractors, radio-controlled tractors, and hydraulic excavators, which are suitable for use on flat fields, steep slopes, and terraced fields, respectively. We established nine plots (20 m×2.5 or 2.0 m) for determining the shrub removal rates (effective field capacities, m²/h) and another nine plots (10 m×2.0 m) for measuring the diameter of removed trees, in an area dominated by multiflora rose (Rosa multiflora Thunb.) and Chinese hackberry (Celtis sinensis Pers.), respectively, with three plots assigned for each mower. The average shrub removal rates of the tractor, radio-controlled tractor, and hydraulic excavator were 7,518, 2,988, and 269 m²/h, respectively, which were notably higher than those of the conventional method using brush cutters (62 m²/h, estimated from national standards). The maximum diameter of trees removed by the mowers (in the same order above) were 17.6, 10.6, and 7.5 cm, respectively. These results indicate that the tractor-mounted flail mower has higher performance for shrubs on flat field and tall trees on moderate slope, with average heights of 159 and 272 cm, respectively.

Commercial forage corn varieties were tested to assess grain production in southern Kyushu in late-spring and summer seedings during the 2019-2020 seasons. In late-spring and summer seedings, seven and nine forage corn varieties, respectively, were evaluated at the harvest time for grain yield and maturity as well as disease and pest damage and stress factors, including root rot, southern rust, ear surface mold, insect damage, lodging, and stalk breakage. Grain production was found to be impractical in late-spring and summer seedings compared with spring seeding assessed in our previous study. The 2-year average grain yield in the top varieties was nearly 9 t/ha in summer seeding, exceeding the < 8 t/ha in late-spring seeding. In both seeding time, southern rust sensitivity leaded to a decline in grain yield. A serious defect was exhibited in late-spring seeding in which moldy ears were prevalent across all varieties, resulting in low grain quality. In summer seeding, mechanical harvest was prevented by failing to reach full ripeness across varieties. It is difficult to improve grain production in late-spring seeding. One potential solution for summer seeding would involve using earlier ripening varieties or seeding earlier than in the present study, although both options require further investigation.

A physical control technique that irradiate yellow lights at night has been developed to suppress moth species. However, the effects of this method on the fall armyworm (Spodoptera frugiperda) and the growth of maize (Zea mays L.) are unclear. Therefore, this study, for two years, investigated the effects of yellow light irradiation on the growth stages of maize, which is significantly damaged by the fall armyworm. In the first year (2021), yellow lights were set up at the edge of a maize field (second cropping season) after sowing (25th August) and irradiated at night time until harvest (29th October). The growth stage of maize was investigated at 51, 59, and 65 days after sowing. The results indicated that yellow light irradiation retarded the growth of maize after the reproductive growth stage, and the degree of retardation depended on the irradiation intensity and distance. In the second year (2022), the timing of yellow light irradiation, which did not cause growth retardation, was examined. The results showed that yellow light irradiation from sowing to the 5-6 leaf stage did not retard growth retardation after the reproductive growth stage; however, light irradiation from sowing to the 9-10 leaf stage and the later stage retarded growth.