Experiments were conducted to evaluate the effect of application rate, growth stage, and tank mixing azimsulfuron, bentazon, MCPA, propanil, or cyhalofop on the efficacy of bispyribac–sodium against early watergrass and late watergrass from rice fields in northern Greece. Mixtures of bispyribac–sodium with the insecticides carbaryl, diazinon, and dichlorvos were also evaluated. Bispyribac–sodium (24 to 36 g ai/ha) applied alone at the three- to four-leaf growth stage provided 89 to 100% control of early watergrass and 84 to 100% control of late watergrass. When bispyribac–sodium was applied alone at the five- to six-leaf growth stage of early watergrass and late watergrass, control ranged from 78 to 100% and 71 to 100%, respectively. Mixtures of bispyribac–sodium with azimsulfuron provided better control of both species at any growth stage than bispyribac–sodium applied alone. On the contrary, mixtures of bispyribac–sodium with bentazon, MCPA, or propanil were less effective on both species at any growth stage than bispyribac–sodium applied alone. A slight efficacy reduction occurred on both species for the mixture of bispyribac–sodium with cyhalofop. Mixtures of bispyribac–sodium with the insecticides carbaryl or dichlorvos showed reduced efficacy on both species, whereas increased efficacy on both species was observed for mixtures of bispyribac–sodium with diazinon as compared with the single application of bispyribac–sodium.
Nomenclature: Azimsulfuron; bentazon; bispyribac–sodium; carbaryl; cyhalofop; diazinon;dichlorvos; MCPA; propanil; early watergrass, Echinochloa oryzoides (Ard.) Fritsch ECHOR;late watergrass, Echinochloa phyllopogon (Stapf) Koss. ECHPH; rice, Oryza sativa L