A review of spray generation, delivery to the target and how adjuvants influence the process

Paul C.H. Miller and M. Clare Butler Ellis, Silsoe Research Institute, Wrest Park, Silsoe, Bedford, MK45 4HS, United Kingdom.

Presented at the Fourth International Symposium on Adjuvants for Agrochemicals, Melbourne, Australia, 3-6 October 1995.


The addition of an adjuvant can influence the processes of spray formation, droplet transport, impaction, retention and coverage of spray on the target surface. Methods of producing agricultural sprays are reviewed and methods of measuring and classifying such sprays are identified. These classifications provide useful information relating to spray behaviour but nozzle performance can be substantially influenced by adjuvants. Studies have shown that the mode of spray formation from flat fan hydraulic pressure nozzles can be changed substantially, influencing droplet size, velocities and the volume distribution pattern obtained. Anti-evaporants influence spray behaviour during transport of spray between the generator and targets.

Behaviour at the target surface in terms of impaction, retention, coverage and uptake can all be modified. To date there is no clear definition of all of the effects of physical parameters of the spray liquid on behaviour. It is concluded that substantial progress has been made in the development of methods for measuring and predicting spray formation and behaviour, but that there is a need to understand how the addition of adjuvants can influence all of the physical processes involved, as well as the chemical and biological effects. Such information will enable adjuvants to be used to improve spray application in a safe and effective way.


Plant Protection Quarterly (1997) 12 (1) 33-38.