Seeds are subject to attacks not only externally but also internally as fungi or bacteria may attach to their coating or even within eventually causing plant diseases. The dangers that threaten seeds are present during storage and after planting. The soils upon which seeds are planted also contain fungi and bacteria that could harm them and the degree to which they could endanger seeds depend upon the condition of the soil at the time seeds are planted, which do not favour fast germination.
Seed treatment had been practiced as early as 60 A.D. when seeds were treated with wine and crushed cypress leaves to deter insects from destroying them while in storage (Munkvold et al. 2006 7). Also, during the Egyptian and Roman periods sap from onion was used; in the Middle Ages, chlorine salts and liquid manure, and; in the 1600s, hot water started to become a ST method, one that is still being used even to this day (Australian Seed Federation 2010). The earliest treatment for wheat seeds was accidentally discovered in the 17th century when a ship carrying a load of wheat grains sank. When grains that got soaked in the seawater were recovered from the sunken ship and were planted they produced plants that have less bunt or stinking smut than the usual crops planted using ordinary seeds. Thus, soaking seeds in seawater became one of the earliest treatments to seeds to prevent bunt until in the year 1750 a Frenchman discovered that salt and lime can control bunt in wheat significantly. The advent of the mercurial compounds in the 1920s, although later banned, had revolutionised contemporary seed treatment (Munkvold et al. 2006 7).