Chemical Control of Barnyardgrass in Rice

ARNYARDGRASS (Echinochloa crusgalli (L.) Beauv.) is the most B serious weed in rice in Arkansas and this and other species of Echinocliloa are a serious problem throughout the rice-growing areas of the world. A limited field survey conducted in August 1957 in the Grand Prairie rice-growing region of Arkansas indicated that 27 percent of the rice fields were infested with barnyardgrass. Presumably the yield of rice on these fields could have been increased substantially by controlling the barnyardgrass. Investigations in Louisiana (1) indicated that isopropyl N-(3chlorophenyl)carbamate (CIPC), sodium trichloroacetate and sodium 2,2,3-trichloropropionate applied 3 days after emergence of rice gave satisfactory barnyardgrass control without reducing yields of rice. However when applications were made 7 to 14 days after emergence the chemicals were ineffective. In Venezuela annual grasses such as barnyardgrass and crabgrass were controlled effectively in upland rice with pre-emergence to emergence applications of CIPC and 4,6-dinitro-o-sec-butylphenol (DNBP) (5). Even though annual grasses emerged late in the growing season, treatments with herbicides increased yields of rice substantially. The purpose of this investigation was to evaluate chemicals and methods for the control of barnyardgrass in rice and factors that influence their use.