Course: Spraying advice | Last Updates: 7th October 2015
Efficiency gains can be made by addressing spray drift and improving filling operations in the yard.
On farms where fewer staff increasingly have more spraying operations to complete, spray timeliness is essential.
Delays to the schedule not only have a direct impact on the bottom line, they also leave crops exposed. The current reliance on protectant applications to keep weeds and diseases at bay means crop yields and quality suffer where treatments are late.
This is illustrated by work done with wild oats, which has shown that by delaying treatment from mid April to late May, wheat yields dropped by 1.2t/ha. This was despite achieving 98-100% control at each timing.
Making the best use of available spray days is a challenge. Even in the dry Cambridgeshire area, nine years of weather data shows that only one-third of the busy April, May and October period is suitable for spraying.
In wetter areas, this figure could be lower, as it is based on a combination of suitable conditions, including wind speed, temperature and rain.
As a rule of thumb, you should be able to spray all your wheat in under three days. And in order to do this, there are two key areas to address – spray drift and filling operations.
Boom height and drift
The further a spray droplet has to fall, the greater the chance it will drift. With that in mind, setting the boom height correctly is the crucial first step.
Booms set at 1m or more above the target are too high. The optimum height is 40-50cm with a 110deg flat fan nozzle – and this applies whether the target is the soil, for a pre-emergence product, or the crop or weed for a foliar spray.
Having the boom at the optimum height improves spray performance and reduces drift. This, in turn, opens up more spraying opportunities – making it an easy win.
By reducing the boom height to the right level, or choosing a less drift-prone nozzle, you can achieve the same level of drift reduction as you would with a one point drop in wind force as measured on the Beaufort scale.
Setting boom height
A simple boom height cable, available from Syngenta, will help set the correct boom height. It also offers a solution for maintaining boom height while spraying – rather than judging it by eye.
Graduated at 5cm intervals along its length, the tie is attached to the boom end and then trimmed to the required height. This is done by using the graduations as a guide – for example, 10 graduations will be 50cm.
The boom can then be adjusted so that the end of the tie just touches the target. In this way, users can optimise the distance that spray droplets fall.
Put the correct boom height together with the optimum nozzle choice, and drift will reduce even further.
Air-induction nozzles are the best for reducing drift. A good example is the Amistar nozzle, which is based on air-induction principles and gives double the work rate for one quarter of the drift.
Research shows that using air induction nozzles is equivalent to gaining four extra spray days a month.
There are efficiency gains to be made in the yard, as well as in the field.
Cutting down the time required for sprayer filling and washing out will improve work rates. It may even be possible to apply an extra sprayer load during one day.
Good examples include choosing products which come in bottles with foil-free caps, so that time spent removing, rinsing and disposing of caps is eliminated. It also reduces the amount of contaminated waste. A saving of 40sec/pack has been recorded – especially useful where products come in smaller one litre bottles.
Similarly, using a product approved for use in both wheat and barley can cut down on the time needed to return to the farm and wash out the sprayer between crops. Estimates suggest a saving of 40 minutes or £70/product change. Of course, it also means fewer products to store and keep records on.
Other savings come from using pre-formulated mixtures during busy times, such as T1 and T2, rather than tank mixes. Products that come in larger packs are also worth considering.
These last three measures mean fewer packs to load into the sprayer, to dispose of and to rinse. This can save up to 10 minutes per fill-up, which goes some way to fitting in that extra sprayer load.
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