A motion analysis system based oil slow-speed video imaging was used to develop a procedure for measuring the dynamic surface tension of liquids at short surface ages using the oscillating jet method. Bohr's equation and Bechtel's inverse method were used to calculate surface tension from measurements of the jet waveforms. Values of surface tension determined by both methods were in good agreement with hardbook values. Surface tensions calculated from waveforms near the jet orifice were found to be similar to values calculated for waveforms further from the orifice. Most agricultural sprays are mixtures of materials, not true solutions, and as such their surface tensions change with surface age. A method of measuring surface tensions at short surface times is essential for predictive models of the effect of adjuvants on the properties of agricultural sprays, especially droplet atomization and droplet rebound from plant surfaces; both of these processes are completed in less than 3 ms.