Weeding efficiency of wheel track nozzles mounted on a self-propelled sprayer

Summary The aim of this study is to evaluate the efficiency of wheel track nozzles mounted at the rear of a self-propelled boom sprayer for the control of weeds in wheel tracks in dry seeded rice field using a vacuum seeder. Weeds often survive in wheel tracks probably because of contact with the wheel immediately after herbicide has been sprayed using boom nozzles. The herbicide used was glyphosate potassium salt solution, a non-selective foliar spray herbicide. The herbicide was applied prior to rice emergence. Herbicidal effects were evaluated on late watergrass ( Echinochloa oryzicola Vasing.), the dominant weed species in the study field. The number of surviving plants was determined one month after herbicide application. There were 5.15 times as many plants in the wheel tracks as in other areas of the field. Use of wheel track nozzles reduced the number of the plants in the wheel tracks by 0.21 times compared with that in wheel tracks when wheel track nozzles were not used.