Top tips for stubble spraying to control grass-weeds
News10 Aug 2016 Abby Kellett
More care and less speed in stubble glyphosate spraying are critical to making the most of its increasingly vital role in arable grass-weed control this autumn, insist leading crop management experts.
Top tips for stubble spraying to control grass-weeds #black-grass #spraying
1. Water volume
- Water volumes of 100 litres per hectare allow you to cover more hectares in a day and get higher concentrations of glyphosate onto the leaf
2. Droplet size
- Where black-grass seedling leaves are small and thin, do not use a coarse spray as this limits droplet numbers, reducing coverage
Roundup technical specialist, Barry Hunt says: “With time at such a premium and effective control of black-grass and other troublesome weeds ahead of drilling so crucial, less-than-ideal pre-planting glyphosate treatment is something you can’t afford these days.
See also: Weed screen explores options for grass-weed control
3. Nozzle type
- 03 flat fan nozzles operated at 2.5 bar are considered the best all-round option
“Apart from wasting time and money and putting extra pressure on hard-pressed pre-and post-em chemistry, an incomplete kill is the fastest route to resistance development.”
4. Boom height
- For the most effective seedling weed targeting and to minimise drift, opt for a boom height of around 50cm and a forward speed of 12km per hour to reduce turbulence effects
5. Alternative nozzles
- Where it is difficult to get the boom down to 50cm, replace the standard flat fan 110 with an 80 degree nozzle to ensure the right spray quality
Agrii spraying specialist, David Felce warns growers that they only have one or two opportunities to tackle black-grass ahead of drilling.
“If you’ve got bad black-grass these can be your most important sprays of the season, so it makes sense to take the time and effort to get your glyphosate application spot on.”
- Avoid sub-optimal conditions such as hot, dry weather, rainfall within a few hours of spraying and hard water
- Use the right rate of glyphosate for the job - typically 540g/ha of glyphosate to control grass-weed seedlings of up to six tillers and up to 1800g/ha for the most difficult perennials
Correct glyphosate targeting is as important as timing according to Mr Felce, who urges operators to spray at the right speed, height and pressure using the most appropriate nozzles as well as the correct rates and water volumes.
- In most situations, adjuvants will not make up for any lack of active ingredient
Source: Adapted from Monsanto technical information