Spraying to meet environmental demands

 

Author Craig Day
Agency Spray Safe & Save

 

 

Heading Efficient Spraying to Meet Environmental Demands “learning to spray with coarser sprays”

 

Spraying is about placing the correct dose of chemical at the right place at the right time. To achieve this, we need to understand more about application then just what water volume we are going to apply over a given area.

 

The Australian Pesticide and Veterinary Medicines Authority (APVMA) have raised the stakes on application management. Without pesticides the world would find feeding itself a monumental challenge, but this does not mean that the community at large embrace the idea of managing pests with chemicals. It is our responsibility to ensure that our management maintains consumer confidence.

 

The APVMA moves to mitigate drift is a response to just that – DRIFT. Drift is defined as the “Off target movement of pesticide outside the intended application area at the time or soon after application.”

 

The Murray Valley drift in 2004-05 summer was a major precursor to the restriction on High Volatile Esters but it was also a symptom of a farming system undertaking change.

 

I would predict that you will see more drift going forward before the situation gets better. As farmers today I believe we are making some decisions that may lead to increased drift risk.

 

What Drives Drift

 

Droplet size

 

 The smaller the droplet, the more chance it will drift. We have also been hung up on putting out fine sprays to achieve better coverage. In a perfect world this may be true, but if your spray unit is producing fine sprays, up to 40% of your application may be too small to fall to ground under the pull of gravity.

 

Wind Speed and direction

 

The APVMA is regulating the minimum and maximum wind speed and there will be differences across chemistries. This makes reading the label an essential part of any spray job.

The introduction of down wind buffer zones will impact on land use and IPM programs. Buffer zones are related to risk associated with chemicals in relation to Human Health, Environment and Trade. Management of the down wind zone will need careful consideration.

 

Temperature and Humidity - Delta T

 

The influence of temperature and humidity on drift and the focus on Delta T has possibly increased the trend for people to spray at night time during the summer time. However this is a situation that needs careful management and assessment. A Low Delta T is potentially a higher risk situation then spraying when the Delta T is at 8.

 

Spray Release Height

 

The height of spray release will greatly influence drift potential. Increasing boom height from 50cm above target to 70cm above target increases drift potential by a factor of 4 x.

 

The trend for new sprayers is to have wider booms which travel faster. There would be many of these that are set well above 50cm above target.

 

High ground speeds will wrap spray droplets back, which has the same influence on droplets as raising boom height.

 

As applicators, we are being forced in some ways to maintain our work rate. To do this, we are demanding machines that are wider, with large tank volumes and improvements in tractor transmissions are also seeing spraying speeds increase. Also, the ability to spray at night is potentially releasing more active constituent in cool stable environments. Labour shortages and the fact that few people are doing more area, can lead to spraying being done in less than ideal conditions.

 

Changes to Farming Mix

 

People blame Grapes or Cotton for drift when they have just been indicators that drift is occurring. They do however, make spray drift obvious in an area.

 

As a farming community, we will have to be extremely careful when we see broad scale adoption of GM technologies as you will have sensitive crop all around (i.e. non GM canola, wheat and barley). The advent of such technology means that we will potentially be releasing Glyphosate on a broad scale in the dead of winter. This will not be the fault of the GM technology per se, but the way we managed the change to the farming mix.

 

Nozzles and Droplet size

 

Nozzles are the part of the sprayer that require the most attention and have the biggest potential impact on the chemicals performance. Nozzles are however largely overlooked and possibly not changed or adjusted to suit the requirements of the chemical being applied. We need to get smart about nozzles and understand more about the chemicals we are applying.

 

Look out for changes to the Label regarding application set up/down wind buffer zones

 

Ask the following Questions

 

 

As an industry, it is important that we make ourselves aware of differences in nozzle design and the impact that this may have on spray deposition and retention. There are vast differences between coarse sprays depending on how they are produced and this will see variations in droplet velocity, retention or droplet bounce. The way the chemical works will determine the type of droplet that you need.

 

Requirements for applicator training

 

It is vital that all training programs that are run in Australia in relation to application and pesticide management are upgraded to ensure participants are being made aware of changes in legislation but the practical aspects of managing the changes.

 

The APVMA direction is placing more pressure on the person applying the pesticide by requiring the applicator to conduct a risk assessment on sprayer set up, the weather conditions and the surrounding downwind environment and to ultimately decide to spray or not. This new approach requires the training providers to improve on the outputs of their programs to ensure that attendance at training has practical relevance to the target audience. If we spray with best practice approach compliance will be achieved.

 

If you are employing someone you need to be confident that training is delivering enough detail to ensure operators are fully aware of drift its management and control options. 

 

Conclusions

 

Pesticide regulation around the world are being tightened. In Europe, some countries have reduced application rates; buffer zones are common in Belgium, Germany, Netherlands, Denmark and the UK. It is worth noting that Australia’s proposed buffer zones are far greater than our European trading partners.

 

Sprayer testing will be a requirement in all EU member states by 2016 and will involve inspection of farmer’s application machinery.

 

If we are to maintain market access in these markets, we must be looking at these changes and trends with a view to develop a self regulated practical approach to reduce the need for further regulations.

 

 

 

Craig Day
Spray Safe & Save Pty Ltd Shadeland 100 Greenethorpe Rd Cowra NSW 2794
craig.day@bigpond.com
phone 0263455818 0439432529