Volume 5, Issue 7 (July 2008)
Investigating the Use of Hydrocarbon Fluids in Seed Treatment Formulations
Currently, available seed treatments are most often applied as aqueous dispersions or water-based flowable formulations of the active ingredients. Historically, alternatives to aqueous-based treatment methods have been disfavored because alternative solvents, mainly organic solvents, were believed to be toxic toward seeds (phytotoxic). Prior work has shown that seeds such as corn, cotton, wheat, and soybean may be treated with certain nonaqueous solvents, such as hydrocarbon fluids (e.g., normal paraffinic, isoparaffinic, dearomatized mixed aliphatics, and aromatics), with little or no negative effects observed to the seed. In the study reported here, further investigation into the use of fluids for seed treatments has been carried out, and more intensive testing of the phytotoxicity of fluids to seeds, utilizing harsher conditions over longer periods of time (cold germination, saturated cold germination, accelerated aging tests), has been completed. Results have confirmed the importance of fluid volatility (higher volatility fluids result in less phytotoxic response by seeds) and of treatment rates (lower treatment rates minimize negative effects). Seed sensitivity is also important. Cotton and soybean seeds are essentially unaffected by fluids, while wheat and corn seeds show relatively large effects, mitigated to some extent by high volatility and low treatment rates. Although the underlying reasons are not known, fluid treatment of seeds resulted in improvements in germination rates in the saturated cold test, to a small extent for cotton, and to a much greater extent for wheat. Overall, these results indicate that fluids can play a role in seed treatments. The use of fluids requires a balance of factors around fluid structure, volatility, treatment rate, and seed sensitivity. The goal of this work is to take the learnings from these studies, apply them to a full seed treatment formulation, and identify advantages of a fluid-based seed treatment formulation over an aqueous-based formulation.