Seed treatment refers to the application of fungicide, insecticide, or a combination of both, to seeds so as to disinfect and disinfest them seed-borne or soil-borne pathogenic organism and storage insects. It also refers to the subjecting of seeds to solar energy exposure, immersion in conditioned water, etc. The seed treatment is done to achieve the following benefits.
Benefits of Seed Treatment:
1. Prevention of Spread of Plant Diseases:
The disease from treatment standpoint may be conveniently grouped under three types-
a) Systemic Disease:
That infect the seed during the harvest or storage period resulting in infection of seed , E. g Bunt or stinking smut of wheat, Helminthosporium blight of barley, loose and covered smut of oats; head and kernel smuts of rye , smuts of millet . Appropriate seed treatment is significantly effective in controlling these diseases.
b) Systemic Diseases:
That infect seed during the flowering stage to become established within the seed and from there within the resulting plant. Such diseases include loose smuts of wheat. Treatment with systemic fungicides, E.g Vitavax has been found effective.
c) Non-systemic Disease:
Diseases that infect seed during the harvest or storage period. Such diseases includes Helminthosporium blight, blotches or blight of barley, oats, rice , rye , sorghum, wheat and Fusarium. These diseases can be effectively controlled by appropriate seed treatment.
2. Seed Treatement:
Protects seed from seed rot and seedling blights. Seed treatment, by its protective coating around the seed, acts as a barrier once the seed is planted to ward off attack by both seed-borne and soil-borne organisms. These organisms affect, all crop seeds and the degree of attack depends upon a number of factors of particular importance are the organisms. Pythium spp, Rhizoctonia and Sclerotium that are present in all soils. They may rot the seed before germination gets well started, or they may kill the seedling before it emerges, or so affect it that it dies after emergence or supervives only as a weakened plant. The responses to protective treatment varies with the kind of crop seed, the vigour of the particular seed, the amount of mechanical injury to seeds, conditions of seed surface and adversity of planting conditions.
The fungicide treatment compensates by protecting these cracks and abrasions from entrance of fungi.
3. Improves Germination:
Seed treatment often improves the standard of germination through the control of seed surface flora, though normally not considered pathogenic; this may infect the seed following moist harvesting and storage conditions. In the germination test it may smother the seed before it has a chance to germinate.
4. Provides Protection from Storage Insects:
The protection of seed from insect damage during storage is of increasing importance with the trend towards processing, treating and unit packaging of seeds at harvest time. For complete protection it is necessary to treat seed with insecticide also. Insecticides are more needed in warm storage than cool storage.
5. Controlling Soil Insects:
This can be done through combination treatment – the process of addition of an insecticide with fungicide for the added protection of the seed and seedling against certain soil insects, such as wire worm and the seed corn maggot. In contrast to storage insect protection, it is a means of giving limited protection to the seed and seedling until it becomes resistant to attack or can survive limited attack. It is not a means of disinfecting the soil.