Test of the control of weeds on the paddy field by the use of 2.4-D (1)

Abstract

Various foreign sources of information have recently shown us that the application of 2.4-D (2.4-dichlorophenoxy acetic acid) is effective for the weed control. Therefore, the writer tested a possibility of adopting this method in paddy condition. From several varied experiments, a spray of 0.05-0.1 percent 2.4-D in the form of either sodium or ammonium salt in water at the rate of 75-150 liters per 10 ares on weeds between the growing rice plants on well-drained paddy field in the mid-or late July has given desirable results, this method was so effective that, with the exception of Echinochlon Crusgalli Beauv. all kind of weeds such as Aneilema Keisak Hassk., Monorkoria vaginalis presl., Lindernia Pyxidaria all., Rotala indica Koehne. ver. uliginasa Miq. cyperus difformis L. Fimbristylis miliacea Vahl., Elatine orientalis Makino, Echipta alba Hassk., Hleocharis acicularis R. Br., etc., were killed within 1-2 weeks, nevertheless no injury to the rice plants was recognized. It may be recommended for the control of weeds on th paddy field to apply 50-75gr of 2.4-D per 10 ares, as it gave as much rice yield as that of the ordinary weeded plot. 37.5gr per 10 ares (0.05 percent solution at the rate of 751. per 10 ares) seemed to be too small doses and 150 gr. per 10 ares too much dose, each of which decreased the rice yields 15 percent and 10 percent respectively as compared with the ordinary weeded plot, although the rice yields of both plots was superior to that of the unweeded plot which about 35 percent less yield than the control.