The challenges of spraying grassland
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David Gurney, field technical manager for Corteva Agriscience highlights the differences between spraying arable crops and grassland
Grassland represents a different spraying challenge to spraying arable crops, with travelling speed likely to be reduced. Grassland typically is a more undulating and uneven surface with hoof tracks, wheelings, poaching and lack of tramlines all making it a slower job.
A recent survey of contractor spray practice indicated the average travelling speed when spraying grassland is 9km/h with a range from 6.5km/h to 10.5km/h. A new- sown ley would probably be smooth enough to travel at a higher speed.
There is a wide range of broad-leaved weeds to control in grassland. They all reduce the amount of grass that grows and is therefore available for the animals to eat. As high quality grazed grass and silage are the cheapest feeds on the farm, livestock farmers are increasingly looking for weed-free leys. As many are not now qualified to spray, or do not have certified sprayers, contractors are being called in more and more.
Corteva Agriscience has the widest range of tried and trusted translocated grassland weed herbicides for the specific range of weeds affecting livestock farms, including Doxstar®Pro, Thistlex®, Leystar®, Envy® and Forefront® T.
Spray targets in grassland vary enormously with docks, thistles and nettles potentially standing taller than the grass canopy, while weeds like buttercups, chickweed and dandelions growing within the grass canopy. Set the boom height according to the weed target. This is normally 50cm above the target (with a 110° nozzle) to avoid overlaps or missed strips.
Make sure to read rain fastness guidelines on product labels. If it rains before the chemical has dried on the leaf, it washes the chemical off before it has penetrated in sufficient quantities. This will then potentially affect levels of control and the presence of chemical in water courses.
The water volumes on the product label are set as a consequence of maximising performance on target weeds and/or from an operator exposure perspective. Follow the guidelines from the manufacturer.
Corteva Agriscience will support the use of all its grassland herbicides at a water volume use down to 200 litres water when using an air inclusion nozzle, which leads to less drift and more coverage of the target weeds. Dropping water volumes further than this is not supported by the manufacturer, is against the label direction and can lead to poor product performance, scorch and increased risk to the spray operator.