Texasweed (Caperonia palustris) Interference in Drill-Seeded Rice

Field research was conducted near Saint Joseph, LA, in 2008 and 2009 to evaluate Texasweed interference in drill-seeded rice. Season-long Texasweed interference at 1 plant m−2 was estimated to cause 5% yield loss. Yield loss from 10 and 50 plants m−2 was 31 and 61%, respectively. Yield loss was primarily due to a reduction in effective tillers per square meter. Thousand-grain weight of rice was not affected by season-long Texasweed interference. Path analysis indicated yield component compensation, i.e., a reduction in effective tillers per square meter probably caused an increase in grains per panicle. However, that effect was not strong enough to reverse the detrimental effect of reduced effective tillers per square meter on rice yield. The critical period of Texasweed interference to cause more than 5% yield loss was estimated to be between 0 and 6 wk after rice emergence. Nomenclature: Texasweed, Caperonia palustris (L.) St. Hil. CNPPA; rice, Oryza sativa L. ORYSA.