In the second exclusive EIO application advice video, Syngenta application specialist Scott Cockburn, explains the best techniques to employ when applying pre-emergence herbicides.
With increased resistance to post emergence herbicides, there’s never been a more important time to ensure you get your pre-emergence application correct.
Before starting any spray regime, it’s a good idea to make a plan, says Scott Cockburn. This should include:
- Stale seedbeds
- Delayed drilling
- Crop rotation
- Seedbed preparation
- Application timing
“Residual herbicides work best when applied to a firm, fine seedbed,” he says. “This will maximise coverage on the soil surface.”
Right on time
When it comes to timing, it’s really important to get the application on as quickly as possible – ideally within 48hrs after drilling, adds Scott. “This ensures it will kill the weeds when they are at their most vulnerable stage.”
Hit the target
For pre-em residual herbicides the target is the soil. It’s easier to miss than some may think, so a good set-up and technique will make a big difference to the application, says Scott.
As usual, boom height, forward speed, water volumes and nozzle selection will all help improve the efficacy.
Boom height and forward speed are closely linked. “We need to maintain 50cm above the soil surface and, ideally, at a speed of less than 12km/hr to protect boom stability. This will also have a significant effect on reducing spray drift.
“Less drift puts more product on the surface, which provides better control when the weeds do eventually emerge.
Volume is crucial
The aim of the pre-em application is to cover the whole surface – creating a ‘cling-film’ effect across the top of the soil – through which the weeds have to emerge. “This means the right water volume can help improve coverage,” he adds. Research shows 200 litre/ha proves the most effective with all nozzle combinations – typically achieving double the control of a 50 litre/ha application and a 30% better result than 100 litre/ha.
Nozzle choice to cut drift
With no crop to catch drift, correct nozzle choice is essential, explains Scott. “We have found 90% drift reduction nozzle such as the Teejet TTI can work very effectively – and in less than ideal conditions.
“In cloddy seedbeds, angled nozzles will reduce the shadowing effects of the clods and improve coverage,” he says.
Follow best practice
- Apply to a find firm seedbed
- Keep forward speed to less than 12km/hr
- Maintain 50cm boom height above the target
- Water volume of 200 litres/ha
- 90% drift reduction nozzles
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