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Choosing a Producer Seed Treating System

Getting the best field benefit from seed treating products requires:
1. accurate seed dosage rates and
2. uniform application to all the seeds.
Otherwise the potential benefits are lost.

Most current products are water-base liquid solutions with high polymer and drying agent content. These are needed to stick the product onto the seed, and dry quickly so it stays attached. Think of them as quick drying latex paint.

Just like field spraying, seed-treating crop benefit is determined by the effectiveness of the product, and how well it's applied.

Producer Seed Treating System Components.

When choosing a seed treating system, ask the following questions to check for applicator effectiveness.

1. How is the product applied?

Originally seed treating was done with gravity drippers, but they lack any means of accurate control, so are poor at delivering accurate rates or uniformity. New treating products are designed to stick where placed, so don't work well with drip type application, which initially places all the product on about 10 % of the seed.

Flat fan spray nozzles are used, but are notorious for plugging with chemical and dust residues. They can plug partially or completely, eliminating any reliable pressure to flow rate relationship. Flow rate is thus highly uncertain. Most flat fan units are not calibrated, so users must try to field calibrate or guess at flow volumes.

Some applicators use 2 nozzles, hoping a bad application can be improved by spraying twice. Unfortunately, reducing the nozzle opening by half makes plugging occur even more quickly.

Controlled droplet Hollow cone nozzles are a 2-part center hole types, used for application of liquid fertilizers and similar products where droplet size control and plugging resistance is required. This makes them a reliable applicator for producer systems.

Spinning Disc applicators are available, but usually not in producer systems due to their higher cost and maintenance requirements.

Higher value producer treating systems should have reliable applicators that resist plugging. They should also be flow calibrated with the chemical, for ease of use and accurate application.

2. Is the seed rate controlled?

Seed flow rates to the chemical applicator must be stabilized, to apply a predictable rate of chemical. This can be done with augers, conveyors, metering rolls or restrictor plates. In many producer-treating setups, it is not controlled at all. This pretty well eliminates any rate accuracy.

Higher value producer treating systems will have some means of controlling the seed rate, and hopefully indicate what that rate is.

3. Where is the product applied?

Seed treating can be applied in augers, conveyors, bean ladders, restrictor gates, custom units, or dumped onto the seed in the seed drill.

Crop benefits from treating are a direct result of how uniformly the seed is treated.

Dumping liquids into an auger or conveyor isn't much use for crop protection. Operating them at half of full capacity exposes more seed to the spray, but still hits only about 1/5 - 1/3 of the seeds with 100 % of the chemical.

The top seeds get a 500 % rate; the bottom ones none. 80 % of the seed is improperly treated. That means only 20 % of the benefit gets to the crop. Not much field help.

Spraying with uncalibrated flat fan nozzles into augers conveyors is a bit better, but not much. It requires field calibration to set each rate, and flat fans plug quickly with dust and chemical residues. Flat fan nozzles are designed to overlap, so most have a flow variance of 30 % from the center of the pattern to the outer edge. The treated seed gets the same variance.

Flat fan spraying into bean ladders yield similar reliability and uniformity problems. Ladders are good velocity arresters, but poor as grain spreaders.

Spraying into augers with calibrated hollow cone nozzles allows accurate rate application; you just can't get it uniformly applied.

Calibrated hollow cone nozzle applicators provide the best application accuracy and reliability, when applying with a one auger treating system.

4. Improved uniformity of product onto the seed yields better field benefit.

To get all the benefit from your seed treatment, you must treat all the seed.

Treating all the seed uniformly requires changing the seed flow pattern before the chemical is applied. Some treaters do this by changing the seed flow into a thin stream; others by spreading it out into an air curtain. Anything that opens up the seed flow to chemical application will usually help, provided it doesn't mechanically hurt the seed by the change.

The only effective seed re-distributor treaters currently on the market for producers are the Flexicoil air seeder unit and the Graham G3. They both deliver over 85 % primary application accuracy.

The Flexicoil on the go unit puts the seed onto a spiral with a thin curtain of chemical. It is quite effective, but has issues with plugging and complexity. It is no longer being sold, but still has many units in service.

The Graham G3 is a high-speed applicator, used in both producer and commercial applicator systems. It comes pre-calibrated for accurate pressure delivery of chemical, and operates at high throughput speed (1200 to 1500 bu. per hour). It is used in conjunction with a seed flow control unit like the TX7 transfer auger, or a restrictor control cone if hung from a gravity discharge bin.

5. Cost - Benefits of Producer seed treaters.

Seed treaters are used to deliver crop production benefits via the seed. Their value to a producer is determined by how well they do this.

Like a field spraying operation; good seed treating products will fail with bad application.

Each producer must decide how much to invest in an applicator, vs. how much field benefit he expects from the product. (see chart)

Producer Seed Treater Alternatives - Fall 2004
Applicator Types?Pre-
Ease of
% of
Benefit Realized
Q.- How is treatment applied to grain?
Q.- Is treatment rate controlled ?
Type 1- No control - gravity drippers
Gravity drops uncalibrated rate
on top of grain flow in auger.
No Not Possible
flow rate changes
as tank empties
50-200 %10-15 %No20%
Easy Treat; Fast Treater, Classic
 Kernel dosage
- .2X-4X
Type 2 - Rate Control/Open discharge
Some control of chemical rate. Liquid drop application onto seed.
No Difficult
No product
flow indicator
50-150 %10-25 %No30%
Agsco; GAP air kegs
 Kernel dosage
- .4X-4X
Type 3A - Flat Fan Nozzle - uncalibrated
Pump sprays into auger or bean ladder
No Possible
but unstable
50-150 %30-40%No40%
Examples: Various Kernel dosage
- .7X-2X
Type 3B - Pressurized Nozzle - Pre-calibrated
Pump sprays controlled rate into auger.
YES Excellent
90-110 %30-40 %Yes60%
Examples: GS A4S Kernel dosage
- .7X-2X
Type 4 - Rate control / Distributed application
Applies treating with high distribution accuracy. Pump cross sprays calibrated rate onto expanded seed curtain.
YES Excellent
comes precalibrated
90-110 %80-90 %Yes85%
Examples: GS G3 Kernel dosage
- .8X-1.2X
Flexicoil Air seeder unit
Pump sprays calibrated chemical onto
grain being swirled in centrifuge.
YES Excellent
90-110 %80-90 %Yes85%
NOTE: Can't be used with Vitavax solution, or on single shooter air seeders. Kernel dosage
- .8X-1.2X
Primary application accuracy is becoming more important. The polymer stickers in the new water base products don't allow re-distribution of initial placing like older solution products did.
(a) - % of required rate that is actually applied?
If the device is uncalibrated, rates will vary widely with color treating guesses.
This will result in significant under or over treating.
Usually primary accuracy depends on whether the device is pre-calibrated, or if not, how easily can it be field calibrated?
(b) - % of kernels receiving the proper primary application chemical dosage?
The balance will get some other rate - 0 to 600 % of required.
i.e. - in auger drippers, 100 % of the chemical is initially applied to about 15 % of the seed.
Kernel dosage will be from 0 (no chemical) to 6X (100 / .15). Rates over 4X can harm seed germination and vigor.
(c) - Seed flow rate control provides much more accurate application rates
Seed flow rate to the applicator (bu./minute) must be set (or guessed at) as a essential part of seed treating.
The accuracy of the seed rate setting is a major component of applying an accurate product application rate.
(d) Realized benefit = total of potential crop improvement less cost of product applied
How much of the potential is available is a direct funtion of the accuracy and uniformity of application
Good products applied with poor applicators lose almost all field benefits
Benefit shown doesn't include the savings with calibrated systems of not overapplying treatment rates.
This can be up to 50 % of chemical cost.
Benefit realized doesn't reflect seed damage from + 3X rate application (grain on top of auger flow).
Treating benefits are increased by higher crop value; higher production potential or larger disease loss.
(e) Flat Fan nozzle flow rates are unpredictable due to their high plugging frequency.
Flat fan nozzles are very vulnerable to plugging with dust and chemical residues due to their narrow opening.
This produces unreliable flow rates when they are used as seed treatment applicators .
Also they are designed for nozzle overlap. This means some seeds gets 30 % more product than others, if they are in the center of the pattern.

Cost / Benefit Analysis of
Producer Seed Treating Systems
1,000 acres Treated
March, 2005
- Treating cost per acre
- $1.60 per bushel x 1 3/4 bushels = $2.80 per acre

- Acres treated = 1000
- Treating Chemical Costs per year = $2,800
Annual Costs and Benefits
Treater Type?Annual
Open discharge
(kegs, easy treat)
Flat fan nozzle units$3,000$3,360$360$60040%
Calibrated hollow cone
- P1, P2
G3 applicator
with seed rate control
Annual Costs
Annual chemical + 1/3 hardware costs. (hardware depreciated over 3 years.)
Total annual potential benefit
3 times chemical costs x treater effectiveness %.
Net annual benefit = Annual Total Benefit less costs.
% of Benefit Realized (treater effectiveness)
(variance due to application rate accuracy, uniformity and seed flow control)

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