Abstract
As barnyardgrass (Echinochloa Crus-galli BEAUV. var. caudata KITAGAWA) is essentially a wild grass, it is presupposed that the grass will easily escape to be a weed on the following rotated paddy field. To control the weed, two experiments in pot and field were carried out. The results obtained were as follows: 1. Although barnyardgrass cultivated on rotated upland field was cut with short interval to prevent the heading, it produced small ears in autumn on the regrowth tillers with only three to four leaves after cutting. So the short interval cutting gave no effect on decreasing the amount of seeds left on the field. 2. The sprouting of barnyardgrass seeds was significantly affected by the method of rice culture. Especially, the transplanting culture after puddling was effective to prevent markedly the sprouting of seeds as compared with the direct seeding culture on upland condition. Late planting was useful to control the weed in comparison with early planting. Both deep tilling and plowing up in land preparation had also significant effects on weed control in comparison with shallow tilling and rotary tilling, respectively. By combining all these effective factors, only 0.1% of all barnyardgrass seeds sprouted from soil without the application of herbicides. 3. In ordinary season transplanting rice culture, barnyardgrass sprouted without any harmful influence on rice plants in the case when herbicides were applied. 4. Barnyardgrass was difficult to control in direct seeding culture of paddy rice on upland condition. Consequently, it is necessary to harvest barnyardgrass before its seed maturation and to till the grassland in the previous autumn.
