Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2002
Publication Date: 7/1/2003
Citation: Gealy, D.R., Wailes, E.J., Estorninos, L.E., Chavez, R. 2003. Rice cultivar differences in suppression of barnyardgrass (Echinochloa crus-galli) and economics of reduced propanil rates. Weed Science. 51(4):601-609. Interpretive Summary: Growing rice varieties that are naturally suppressive to weeds may help farmers reduce herbicide use and input costs while maintaining high yields. Field studies were conducted to evaluate the natural weed-suppressive potential of four U.S. and three foreign rice varieties, and to determine the economic benefit, if any, of simultaneously reducing herbicide rates. Rice yields generally increased and weed growth decreased with increasing herbicide rates, but foreign rice varieties suppressed weeds significantly, and produced higher grain yields than U.S. varieties with or without herbicide. Thus, herbicide provided less weed control benefit to foreign varieties than to U.S. varieties, and potential economic returns were greater for the foreign varieties. These results indicate that if weed- suppressive rice varieties could be perfected, less herbicide would be necessary to produce rice, which could improve both the economic bottom line for farmers as well as reducing impacts of herbicides in the environment.
Technical Abstract: Field studies were conducted to evaluate the weed-suppressive abilities of four U.S. ('Starbonnet', 'Kaybonnet', 'Lemont', and 'Cypress') and three foreign rice cultivars ('PI 312777', 'Guichou', and 'Teqing'), and to analyze the economic benefit of reducing propanil herbicide rates. Yields increased and weed biomass at harvest decreased with increasing propanil rates. The foreign rice cultivars consistently suppressed barnyardgrass and consequently produced higher grain yield with or without propanil application. The economic benefit of using propanil was lower for the foreign cultivars than for U.S. cultivars. The foreign cultivars produced higher rough rice yields resulting in higher potential net returns compared to the commercial cultivars. However, this advantage in net returns to foreign cultivars (especially PI 312777 and Teqing) was reduced when adjusting for their lower milling yields. These results suggest that the use of weed-suppressive rice cultivars in conjunction with reduced herbicide rates can be effective and economically profitable, and could be useful in alternative weed management strategies for rice.