Influence of temperature on physical properties of non-aqueous pesticide formulations and spray diluents: Relevance to u.l.v. applications

The viscosity, surface tension and volatility of a range of ultra‐low‐volume (ULV) spray diluents and pesticide formulations were measured at 5°C and 20°C. For u.l.v. application of 1.0 to 1.5 litre ha−1 through conventional boom and nozzle systems or rotary (Micronair) atomisers, it is concluded that the spray medium should have a viscosity of ⩽30 mPa s at 20°C. The surface tension values covered only a narrow range and showed little temperature dependence. There was no clear optimum and all surface tensions within the range measured would appear to be acceptable for ULV applications. The volatility factor, 1/(A.T1/2), where A represents the percentage of non‐volatile material in the spray mixture and T1/2, the half‐life (minutes) of evaporation, should be