Seed treatment is a rapidly growing segment of the agricultural chemical industry. Two factors have contributed to this. First, the technology of building crop protection and/or specific attributes into the genetic makeup of the plant has led to a significant increase in the cost of the seed. Second, seed exposure has increased because it is being planted earlier into cold, often hostile, no-till soils that provide a refuge for soil borne diseases and insects. Seed treatments provide a way to protect the farmers' investment by controlling specific diseases that affect seeds prior to, during and after germination.
Historically, seed treatments are applied as water-based flowable formulations but these water-based systems have deficiencies. This study examines the use of hydrocarbon and oxygenated solvents as possible alternatives to water. Solvent-based systems offer added flexibility to the formulation of seed treatment products. If solvents are to be used in this application, a critical first question, which must be addressed, is their phytotoxic effect on the seed. Different types of hydrocarbon and oxygenated solvents of differing molecular weights have been screened with sensitive varieties of major crop seeds (corn, soybean, wheat, cotton). Rates of germination will be discussed as they are influenced by the type of solvent, its volatility and the treatment rate.
It will be shown that selected solvents can be safely used in a seed treatment program and that, within a given solvent type, the key to solvent selection is to minimize contact time with the seed by using a more volatile solvent or a lower treatment rate.