CDA spraying on water sensitiv paperMost agrochemicals are applied as liquid sprays, with the spray liquid broken up to be distributed over the target area. Whilst it is obvious that no benefit will result from dumping the entire volume of spray liquid in one spot, it is not so obvious that breaking up the spray liquid unevenly - and thus also getting uneven distribution of the spray liquid over the target area - can be nearly as wasteful. This waste not only costs money but results in unwanted and unnecessary contamination of the environment.

For most spray applications there are particular spray droplet sizes which will be most effective in hitting the target and achieving the desired biological result. In pesticide application, for example, different pests present different targets depending on their size, location and behaviour, thus different spray droplet sizes will be best for different applications.

CDA versus Nozzle

Controlled Droplet Application (CDA) means producing only the optimum sizes of spray droplet for the particular application. This is achieved by specifically designed spinning disc rotary atomisers which break up the spray liquid very evenly, resulting in a narrow range of spray droplet sizes. Micron pioneered the CDA technique and is the world leader in the development of spinning disc rotary atomisers.

Most spraying machines still break up spray liquid by squirting it under pressure through a hole - commonly referred to as anClose-up of hydraulic nozzle detailing variation in droplet size.hydraulic nozzle. The hydraulic nozzle - introduced over a hundred years ago - breaks up the spray liquid very unevenly, resulting in a very wide ,range of spray droplet sizes. Although some of the spray droplets produced will be of the required sizes, most will not - with vast variations in the amount of chemical between the smallest and largest spray droplets (commonly over one million to one).

Very large and very small spray droplets are both wasteful, and will not generally even hit the target. The very large spray droplets end up on the ground and the very small spray droplets drift - either into neighbouring areas or into the atmosphere - thus wasting much of the spray and contaminating the environment. This wasteful inefficiency also means that hydraulic nozzle sprayers have to use much more spray liquid than is actually necessary to do the job. To fetch, carry and spray this extra liquid costs time, effort and money for both the small farmer in the developing world carrying out most jobs manually or the large mechanised western farmer

CDA discThe waste and environmental contamination resulting from spraying pesticides through hydraulic nozzles is causing increasing world-wide concern. CDA offers the way forward in improving spraying efficiency, eliminating waste and safeguarding the environment, as shown by studies in many countries. The UK Royal Commission on Environmental Pollution recognised the important advantages offered by CDA and called for increased research on CDA by government and the chemical industry.

The efficiency of CDA allows low and ultra-low volumes of spray liquid to be used. This logistical advantage can be of critical importance in crop protection, allowing effective spraying programmes to be undertaken quickly in non-mechanised agriculture such and greater spraying productivity in mechanised agriculture. Being able to apply pesticides accurately, quickly and cost - effectively when needed gives the opportunity of fully implementing Integrated Pest Management programmes, with reduced overall pesticide usage.


CDA (Controlled Droplet Application) technology offers a wide range of economical and environmental benefits which include:

Operational efficiencies:

  • Cost savings due to reduced volume of spray
  • Even droplet distribution and uniform droplet size produce better spraying results
  • A considerably faster spraying operation

Increased productivity:

  • Considerably less spray liquid is needed compared with conventional sprayers
  • Consequently the amount of time and effort required are considerably reduced 
  • Hand-held sprayers incorporating CDA reduce physical effort as strenuous pumping is eliminated 

Improved chemical efficacy:

  • CDA technology improves target coverage and spray droplet retention  

Safer Spraying:

  • Operator errors due to fatigue are reduced as the process is less arduous than high volume nozzle spraying 
  • Fewer mixing and filling operations where operator contamination is most likely

Reduced Environmental Impact: 

  • Reduced chemical and water requirement 
  • Lower contamination of soil compared to nozzle spraying thanks to low-volume, targeted application