David Felce of Agrii and Midloe grange farm gives his advice on applications of pre-emergence black-grass products like Liberator. The first factor David advises considering when applying pre emergence treatments is the spray quality; a greater number of spray droplets will give a better coverage and thus a better surface seal with the herbicide. Achieving this is a trade-off between nozzle choice and operating pressure, an 04 of 05 flat fan operating at three bar pressure will typically give a medium spray. Air inclusion nozzles sometimes have a coarser spray, even when operated at higher volumes. The other factor which can help with pre-em applications is nozzle angling can help by giving better coverage of an irregular surface such as a seedbed. Finally higher water volumes, up to three hundred litres, delivered either through twin-lines or larger nozzles can give better coverage and have been shown to give better control of black-grass.