Development and implementation of a laboratory spray device and rainfall simulator for retention research using small amounts of agroformulations

BACKGROUND: Rainfall greatly affects the retention of foliar‐applied agroformulations. Improving their resistance to wash‐off is therefore of great importance in spray applications. When developing such formulations, small‐scale laboratory assays are generally required. A set‐up for retention studies using only small amounts of agroformulations (<0.5 L) was developed. The set‐up consists of a spray device and a rainfall simulator. The effect of rain quantity (1, 3, 6 mm) on the spray retention of agroformulations was evaluated using this set‐up. RESULTS: The data showed that uniform and repeatable spraying was achieved with the small‐scale spray device (coefficient of variation 23.4%) on potato pot plants (Solanum tuberosum L.). Rain quantity significantly affected the spray retention. Approximately 40% of the initial deposition was lost after 1 mm of rain at an intensity of 25 mm h⁻¹. Additional losses decreased with increasing volumes of rain (65 and 80% loss after 3 and 6 mm of rain respectively). CONCLUSION: Future studies could implement the set‐up to evaluate the effect of different rainfall characteristics and formulations on spray retention in order to improve the rainfastness of agroformulations. © 2016 Society of Chemical Industry