Rice cultivar differences in suppression of barnyardgrass (Echinochloa crus-galli) and economics of reduced propanil rates

Abstract

Field studies were conducted to compare the barnyardgrass suppression by four U.S. (‘Starbonnet’, ‘Kaybonnet’, ‘Lemont’, and ‘Cypress’) and three highly competitive, high-yielding Asian cultivars (‘PI 312777′, ‘Guichao’, and ‘Teqing’). The economic consequence of applying less than the recommended propanil rates to these cultivars was also evaluated. Grain yields increased, and barnyardgrass biomass decreased with increasing propanil rates. With or without propanil, the Asian rice cultivars consistently suppressed barnyardgrass more and consequently produced higher grain yields than did U.S. cultivars. The economic benefit derived from propanil application was less for Asian than for U.S. cultivars. Asian cultivars produced higher rough rice yields, resulting in higher net returns (not adjusted for milling) than did the commercial cultivars, but this advantage was usually reduced when adjusting for their lower milling yields. These results suggest that growing weed-suppressive Asian rice cultivars in conjunction with reduced herbicide rates could be an effective and economical weed management strategy for rice in the southern United States. However, first, their plant type and grain quality characteristics must be improved.