Techniques: Film Coating

Film coating has gained popularity as a seed-coating method over the last several years because of worker safety considerations.

Encapsulation for seeds that don't require pelleting

Film coating is often used on seed species that do not require pelleting for precision planting (e.g. the Brassica speciies) but do need some encapsulation to help with the application of plant protectants.

Encapsulation of plant protectants by film-coating insures a uniformity of application superior to the alternative method which is slurry application. When plant protectants are sealed to the seed with encapsulation, the protectants work in a targeted area. Dispersal of the pesticides into the environment is minimized. The full dosage originally applied to the seed becomes available to fight against the pests in the target environment. In addition, worker exposure to harmful dusts is minimized.

Other advantages of film coating include:

  • Increased flowability in the planter caused by better "slippage" between individual seeds.
  • Increased visibility of seed in the soil.
  • Seed treatment identification by using different colorants.
  • Dustless planting conditions (encapsulated pesticides).

Some disadvantages of film coating include:

  • Plant protectants that inhibit germination may not be used because of inadequate separation between the seed and the active chemical.
  • Seed size and shape and weight are not altered sufficiently to make a dramatic difference in plantability.
  • Polymers and plasticizers in the film coating may be toxic or inhibitory to the seed species - seeds of different species can have different sensitivities to the same film coating chemical.