How can you get the spray timing right when the weather and workload conspire against you? Syngenta application specialist Tom Robinson examines the gains from reduced drift and faster sprayer filling

Why efficient spraying?

How to spray all of the farm's cropping in the limited number of available spray days is one of the key challenges facing many growers. Weather data recorded over nine years in the so-called "dry" county of Cambridgeshire show, during the busy spray timings of April, May and October, only around a third of the month was suitable for spraying. This was based on suitable conditions of wind speed, temperature and rain. In wetter areas, these figures could be lower.

But that's only half the story. With many weeds, pests or diseases, for every day that treatment is delayed, crop yield suffers. Work with wild oats has shown delaying treatment from around mid April to late May reduced wheat yield by 1.2t/ha. That was despite achieving 98-100% control at each timing.

As farms get larger, but often with fewer staff, efficient and timely spraying is not only important to simply "get the job done" but it can also have a direct impact on the farm's bottom line. As a rule of thumb, you should be able to spray all your wheat in under three days.

What can be done?

Among the many factors that can affect the ability to achieve this, two of them stand out as being possible to do something about:

• Drift - which reduces spraying opportunities
• The efficiency of filling operations in the farm yard.

Video one (if you cannot see the video, click here)

Boom height and drift

The further a spray droplet has to fall, the greater the chance it will drift. In fact, a key component of reducing spray drift is setting the boom height correctly. Despite this, many sprayers still operate with booms set too high - at up to 1 metre. In reality, 40-50 cms from the target is optimum for a 110° flat fan nozzle - this applies whether the target is the soil for a pre-emergence product or the crop or weed for a foliar spray.

By lowering the boom to the optimum, not only can spray performance be improved, but drift reduced and therefore more spraying opportunities opened up (more to come on boom set-up in a future Academy).

To put this into perspective, consider the following:

• At a wind speed of force 4 you must not spray
• However, by either reducing boom height to the optimal level, or choosing a less drift-prone nozzle, it is possible to achieve the same level of drift reduction as with a drop of 1 level of wind speed on the Beaufort scale.

Setting boom height

A simple boom height cable tie available through Syngenta's Intelligent Farming initiative can help set boom height accurately. It also provides a simple yet effective solution for maintaining boom height while spraying, rather than judging it by eye.

Specially graduated at 5cm intervals along its length, it is simply attached to the boom end and trimmed to the required height using the graduations as a guide (for example 10 graduations = 50cm). In this way, by adjusting the boom so that the end of the tie just touches the target, users can optimise the distance that spray droplets fall.

Nozzle choice

Of course, combining correct boom height with optimum nozzle choice can help to reduce drift further.

Air induction nozzles are particularly good at reducing spray drift. The Amistar nozzle, for example, uses air induction principles and can give double the work rate for about a quarter of the drift.

Video Two (if you cannot see the video, click here)

Filling efficiencies

The process of spraying itself is only one area where efficiency gains can be made. There are also gains to be had in the yard.

Anything which cuts down the time required for sprayer filling and the amount of washing out can improve work rates - to the extent where it may even be possible to apply an extra sprayer load during the day.

As a simple example, choosing products which come in bottles with foil-free caps eliminates the time for removing, rinsing and disposing of foils. Importantly, it also reduces the amount of contaminated waste. In all, it could save about 40 seconds per pack, so could be especially useful for products in smaller 1-litre bottles.

Similarly, using a product which is approved in both wheat and barley can cut down on the time needed to return to the farm to wash out the sprayer between crops - with estimated savings of 40 minutes or £70 per product change for returning to the farm to wash out and refill. It also means fewer different products to store and keep records on.

There are also time savings from using pre-formulated mixtures during time-critical periods such as T1 and T2 - rather than DIY tank mixtures. You should also consider products which come in larger packs.

Using a ready-formulated mixture means fewer packs to load into the sprayer, fewer packs to dispose of (important given the imminent burning ban) and, most important of all, fewer packs for rinsing. Typically, this could save as much as 10 minutes per fill-up, which can stack up significantly when looking to fit in that extra sprayer load during a day.

In all, these simple changes could mean less time, less hassle and less disposing of waste.