Seeds are increasingly coated chemically as a delivery system for chemicals and biologicals to the field and as a means of avoiding protest against excessive crop spraying. Thus chemicals enter the growing cycle at the point of planting. Time-release pesticides and fungicides on the seeds slowly leach into the soil and, from there, may be absorbed by the plant. It is predicted that after generations of seeds have been treated with chemicals, the plants are no longer able to develop a pest resistance of their own. Naturally occurring immunities are slowly eliminated from the plant.