Pesticide information box

v. 4/5/2010

What is spray efficiency?

It is not always appreciated just how inefficient spray operations are in practice. Graham-Bryce [1] reviewed the efficiency of utilisation of crop protection chemicals in various pest control situations and estimated that:

"Efficiency" of spray application is determined by the complex phenomena that govern droplet transport from the nozzle to the target, which are described in standard texts. As a practical measure, Courshee [2] coined the term Deposit per Unit Emission (DUE) to describe the amount of pesticide recovered downwind in the target zone, relative to the volume emitted from the spray nozzle (originally in locust control operations). DUE is thus an overall measure of efficiency, permitting valid comparisons of spray recovery. It is usually expressed in units such as ml/m2 (mean quantity recovered in a unit area) per ml/m (liquid emitted over a unit of spray track).

Operationally, a measure of economic efficiency is:
Work rate: the amount of ground (or crop) treated per hour/day and is linked to VAR. It is an important factor under certain circumstances, for example:
i) when the cost of labour is high,
ii) when a quick response is needed to a pest population that has exceeded an action threshold (especially if it is rapidly reproducing), or
iii) in migrant pest control.


1. Graham-Bryce, I.J. (1977) Philosophical Transactions Royal Society London B. 281: 163-179

2. Courshee, R.J. (1960) Annual Review of Entomology  5: 327-352.
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