Seed Treatments and Seed Coatings
The underlying theme of all the 2016 ASTA Seed Meetings was that by 2050 global food production must double to meet demands. Every seed counts! Longer crop protection methods are needed as well as diversified modes of action to protect our seeds such as seed treatments and seed coatings.
Seed treatments and seed coatings need to be tailored to crop type, soil characteristics, regional climate, local pathogens and pests, and application equipment. Seed solutions include insecticides, fungicides, biologicals, inoculants, functional coatings. Fungicides and insecticides are used to combat disease and insects. Seed coating materials are designed to retain actives on the seed, increase flow ability, and increase plantibility. The nutrients, biologicals, and inoculants added to seed treatments and seed coatings can:
- mitigate loss from disease and pests,
- extend the growing season,
- mitigate risks associated with environmental changes,
- provide nutrients for seedling vigor,
- manage drift and dust issues.
When developing a seed coating system dispersion, suspension, loading, volume, drying time, efficiency rates, and biological stability all need to be considered.
Seed Coating Components and Considerations
Functional coatings are usually polymer-based technologies intended to provide adhesion and seed flow. Functional coatings need to be compatible with fungicides, insecticides, nematicides, biologicals, and inoculants. Factors to consider when using polymers include seed flow, dust control, abrasion, and dry time. The seed coating colorants are applied at the end of the process. Encrusting and pelleting can also be performed to change the size of the seed, making very small seeds bigger. This makes planting easier by making the seed size more uniform.
Actives and Additives
Additives include fungicides, insecticides, biologicals, inoculants, and seed coating colorants.
Biologicals (also called microbes or probiotics) are added to seed coatings to complement classical see treatments. Biologicals protect seeds and seedlings after germination by:
- colonizing the roots to protect them,
- increasing the availability of nutrients,
- enhancing plant growth,
- increasing resistance to disease,
- deterring pathogens and pests, and
- increasing resistance environmental conditions such as heat, flooding, and drought.
One of the challenges when using biologicals in coatings is to make sure that the other ingredients in the coating do not kill the living organism.
It has been found that microbes do not work individually but in community, synergistically. Diverse microbial communities support resilience and productivity. Projected biologicals industry is $500-$600 million by 2020.
Inoculants provide nitrogen for host legume plants, resulting in stronger plant growth.
Upgrading is the process to remove lower quality seeds. Example: add water and the floating seeds are low-quality – good quality seeds sink.
Priming seeds involves initiating and then halting germination. Primed seeds are ready to germinate faster than non-primed seeds.
Disinfection methods include radiation, hot water, chemical methods, and steam.
Seeds Treatment and the Environment Committee
In Canada, new regulations restricting the use of neonicotinoid (neonic) treatments were put in place on July 15, 2015. Treated seeds are now governed by the pesticide act and the use of neonics are restricted and monitored. One study evaluated the relationship between seed dust and bee mortality and noted that the mortality dropped in 2015. It is being theorized that the drop may be due to newly implemented seed dust control measures (seed coatings which stopped neonics from becoming airborne).
The EPA is still evaluating the neonic-bee correlation and is calling for additional studies.
Seed Association of the Americas
Eleven countries from the Americas are members of the Seed Association of the Americas. They come together to discuss issues that affect the transport of seeds between countries as there is international concern about the spreading of disease/pests through seeds. The group spoke about phytosanitary requirements, biotechnology (new breeding techniques and low level presence in seeds), seed treatment (label requirements, upcoming regulations on biologicals, main crops of concern), and intellectual property determination though the use of molecular markers.