Binder Selection

Critical to the success of any seed coating is the binder that adheres the coating to the surface of the seed. Addition of the binder, also known as a “seed sticker,” requires a good deal of precision. Too much binder, and the coating is held too tight, delaying germination of the seed. Too little binder, and the seed pellet is likely to chip or crack. Along with having less fertilizer present for the seed, these chipped or cracked coated seeds can jam in the hopper during planting, causing skips and gaps.

If precision application of a binder is key to good seed coating adhesion, then which binder is best to apply? There are a variety of options including sugars, gums, starches and cellulose. Although each has its own advantages and disadvantages, repeated studies have raised methyl cellulose (known commercially as METHOCEL™) to the top of the list for consideration.

One important factor when evaluating any binder is the effect it has on the germination of the seed. If the wrong ingredient is added to the seed coating, the seed may be rendered inert. METHOCEL™ cellulose ethers will not adversely affect seed germination. It has low toxicity to plants which further validates its suitability as a binder.

Besides being safe for use, the binder must be good at binding. In a 1984 study by Hathcock (et al) methyl cellulose was shown to have the best retention rate of lime applied in a coating. Another benefit to METHOCEL™ is that the binder does not promote unwanted seed clumping.

One final thing to consider is the addition rate of the binder. The seed coating is intended to focus nutrient and treatment around the seed, and a bulky binder takes away from this. So, which is the most efficient binder? METHOCEL™ can be added at a very low rate (1–5% w/v) compared to other binders which may require use of up to 45% w/v. Utilizing METHOCEL™ leaves more room for the coating to serve its purpose.

If you would like to learn more about METHOCEL™ or discuss other aspects of your seed coating formulation, our dedicated team wants to be a resource for you. Click below to ask a question or request a sample today.