Precision Seed Coaters

INTRODUCTION

Coated seed was first manufactured in Canada in 1977. It was readily accepted by most users and now has a definite role to play in North American agriculture. Today’s coated seeds (Precision Cote® and Rhizoseal®) have many advantages to offer the forage grower. These include a most effective method of preinoculation, which also allows legume seed to be safely mixed with fertilizers. Coating (Precision Cote® and Rhizoseal®) also offer significant benefits to the seedling from the starter fertilizer package contained in the coat which is particularly important under adverse soil conditions).

CHEMICAL INCORPORATION WITHIN THE SEED COATING

Although now well entrenched in North American agriculture, coated seed may not have yet realized it’s full potential in the agricultural industry. Precision Seed Copaters and their sister company Canadian Seed Coaters’ research and development staff have investigated the feasibility of adding agricultural chemicals to forage seed coatings. Initially, our main interest was the safe and effective application of Apron to alfalfa and turf seeds. However, we know now that the simplest and safest way to treat any seed with virtually any agricultural chemical is by incorporating it within a seed coating. The principal benefits to be gained by this method of application are:

1) Energy Savings. The incorporation of agricultural chemicals within a seed coating will help farmers to reduce the cost of chemicals. Even more significant, however, would be the savings in time as well as the cost of fuel and labor to the farmer if he were able to apply herbicides already coated onto the seed.

2) Uniformity of Application. Many sprays and seed treatment methods used can be extremely wasteful and thus become far more expensive and unreliable than they need be. This is because spray can be lost due to "drift" and that many chemical treaters can "miss" a significant portion of the seed that passes through them. During the coating process, flowable formulations of chemicals can be used by thoroughly mixing them with a liquid adhesive, which contains the required chemical. Thus, we can be 100% certain that if the seed is coated, it must contain the adhesive and any chemical that has been combined with the adhesive.

3) Effectiveness of Treatments. All our studies to date show that applying chemicals in this manner will not decrease the efficacy of the chemical. In fact, it seems reasonable to assume that since the chemical is contained by the coating in the immediate vicinity of the seed, it may be more effective. We also noted that because the chemical is not placed directly on the seed, but separated by a thin layer of adhesive (or in some cases contained within the coating itself), any toxic effects to the seed are reduced.

4) Human Toxicity Factors. The majority of agriculture chemicals used, particularly insecticides, are hazardous to humans and many cases of accidental poisoning are reported each year. Coated seed ensures that only qualified personnel have to handle these chemicals (during the coating process). Farmers would not come into contact with the chemicals either during their application to the seed or during seeding (the outside of the coat is sealed by a hard layer of adhesive which ensures that the chemical is contained within the coating), thus protecting the end user of the product. The coating also acts as a "marker" to ensure the seed is not inadvertently used as food or feed.

Research has been directed towards solving the problems caused by weed infestations in forage crops. Initial research on this project was carried out by the U.S. Department of Agriculture at Prosser, Washington. This research demonstrated the possibility of the infusion of the herbicide Eptam (EPTC) into a seed coating, offering a new and intriguing method of weed control. It also highlighted numerous problems with the production and packaging of such a product.

Our first major problem was adding the required amount of liquid Eptam without reducing the physical quality of our coated seed products. We found that this could be done by increasing the amount of coating on the seed, thus allowing the seed to absorb more liquid. However, this meant that our experimental coated Eptam product contained less seed and necessitated an increase in normally recommended seeding rates. Other problems yet to be fully investigated include the possible toxic effect of Eptam on rhizobium and methods of packaging and storage.

Eptam is a particularly volatile herbicide. The fact that it can be applied in the seed coating and yet kill many annual weeds and grasses, four to five centimeters from the seed, demonstrates how rapidly it can move through the soil. As Eptam is so volatile, the seed coating cannot contain it on the seed for any significant period of time. Therefore, new packaging methods must be developed to ensure the Eptam remains around the seed until planting time.

The intriguing prospects of herbicide coated seed led us to seed preliminary trials in Canada. Our own trials at Brampton, Ontario, were seeded using alfalfa which had been treated with Eptam ten weeks prior to seeding. 

CONCLUSION