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Friday, March 19, 2021

Seed Treating Best Practices

While including a seed treatment is a good management tool for protection against various seed and soil-borne diseases, simply treating the seed is not enough. Even distribution of seed treatment on every seed is essential to get the full benefit of the seed treatment. The Bayer SeedGrowth® team has developed some videos to demonstrate this process. The following are some best management practices for seed treating success.

Example image: untreated (left), poor seed treatment distribution (centre), and even seed treatment coverage (right)

Figure 1. Seed treatment coverage: untreated (left), poor seed treatment distribution (centre), and even seed treatment coverage (right). All seed from same sample and infected with Fusarium graminearum.

Before you start:

Clean the seed

Minimize chaff and dust that can prevent seed treatment from sticking to the seed and adds unnecessary bulk to the treatment mixture (Figure 2). Dust and other foreign particles will attract seed treatment, impeding proper coverage while also causing build up on treating and seeding equipment.

Example image: Cleaned seed (left) and Dirty seed (right)

Figure 2: Cleaned seed (left) with seed treatment sticking to the seed, providing protection to the crop. Dirty seed (right) with seed treatment sticking to the chaff rather than providing thorough seed coverage and protection.

Test the seed

Have a lab conduct a fungal scan, germination test, and vigour test. It may be best to select a different seed lot if the germination rate is low, if there is a wide spread between germination and vigour (more than 10%), or there are high levels of very pathogenic diseases. Pathogens to note on a fungal scan for cereals are Fusarium graminearum, Fusarium species, Cochliobolus sativus, and smut. When reviewing the seed test, consider the combined total infection rate of these pathogens as well as the individual infection rates. Alternaria, Cladosporium, and Epicoccum may be reported on a fungal test but these are weakly pathogenic and not likely to impact crop development. For pulses, Ascochyta and Fusarium species should be assessed. Refer to Provincial guidelines for maximum pathogen levels when selecting a seed lot. Seed treatment can help prevent plant infection from low levels of seed-borne diseases and from inoculum found in the soil.

Ensure the seed is warm and dry

Frozen seed can cause the seed treatment to flash-freeze on the seed rather than mixing and drying. Additionally, when frozen seed warms up, moisture can move to the outside of the seed (commonly referred to as “re-wetting”). This can slow drying of the seed treatment and prevent the seed treatment from adhering to the seed. In contrast, warm seed can absorb seed treatment quicker. One way to help warm up seed in the bin prior to treating is to turn on the aeration fan on a warm day. Seed should also be dry by grain standards (14% for wheat). Higher moisture seed takes longer for seed treatment to dry and properly adhere.

Comparison: seed treated while cold (left) compared to warm seed (right)

Figure 3. Seed treatment coverage comparison on seed treated while cold (left) compared to warm seed (right).

Treating the Seed

Step 1: Read and follow the label directions

Full instruction on proper application techniques of the seed treatment can be found on the label.

For safety, wear personal protective equipment that protects you from exposure to chemicals as directed by the label.

Step 2: Mix the seed treatment

Mix according to the directions on the package. Be careful not to overmix. If required, use the water volume specified for the seed treatment product.

Check the label for rinsate directions at this stage. Consider rinsing seed treatment jugs directly into the treater for ease of clean-up. In this case, rinse water is part of the total water volume and should be measured to prevent over-dilution of the seed treatment mixture. Ensure the application rate is adjusted according to the amount of water added with the rinsate.

Step 3: Calibrate the equipment

To properly treat seed, both the seed and product flow through the treater must be measured and calibrated to ensure the correct volume of product is being applied to the mass of seed. Once your equipment is calibrated, treat a portion of seed and adjust the equipment if required. Ensure the treating rate is set according to the product label.

Step 4: Treat the seed

Throughout the treating process, visually inspect the treated seed to ensure thorough, even coverage. Changes in environmental or seed temperature and humidity may all require adjustment.

Handling fragile seed: Consider using conveyors and let down devices to gently handle fragile seeds while moving them to the treater. If using an auger to transport fragile seed prior to treating, run the auger full and slow.

Regardless of seed type, overhandling of seed may damage the seed coat. Consider incorporating seed treating as one of your transporting mechanisms to reduce overhandling. Secondary mixing through an auger is an opportunity to ensure good seed coverage while also transporting treated seed to the truck.

Step 5: Secondary mixing

Secondary mixing is critical for complete coverage on the seed. An auger or any screw-type mixing device can be used for secondary mixing. When using an auger for secondary mixing, it is best to run the auger at a maximum of two-thirds full. A full auger does not allow seed to mix quickly enough as seed moves up in the auger. Check coverage and adjust auger speed accordingly. If treating pulses, a conveyor may supply limited secondary mixing.

Example image demonstrating the effect of secondary mixing.

Figure 4. Demonstrating the effect of secondary mixing. From left to right: untreated, treated without secondary mixing, treated with secondary mixing.

Example image of seed treatment coverage simulation of a full auger (left) compared to a half-full auger (right).

Figure 5. Seed treatment coverage simulation of a full auger (left) compared to a half-full auger (right).

Step 6: Allow adequate time for the seed treatment to dry on the seed

This can help prevent clumping or packing of seed, bridging in trucks or bins and metering issues during seeding. Dry time is dependent on environmental and seed temperature and seed moisture content.

Step 7: Clean the treating equipment

Commercial grain must not be contaminated with seed treatment. Consider using separate equipment for seed treating that will not be used for handling commercial grain. Where this is not possible a thorough equipment cleanout is necessary. If equipment will not be cleaned out until later, consider labelling this equipment in such a way that it will not be accidentally used to handle commercial grain.

  • Thoroughly sweep or vacuum all surfaces. Check pinch points where seed could get caught. Disassemble racks, tarps and other areas where seed is caught.
  • Blow out tubing pipes or angle irons on equipment with compressed air. Ensure you are in a location away from pollinators and pollinator habitat or forage.
  • Pressure wash equipment with warm or hot water and an industrial cleaner such as Spray Nine® cleaner.

Step 8: Dispose of treated seed, wash water, residues and containers according to the seed treatment label directions

Seeding all the treated seed is a simple way of cleaning up without additional process. Containers may be recyclable, returnable or refillable. Check the package and label for additional direction.

For disposal of unused product, contact the provincial regulatory agency or CleanFARMS.

Step 9: Assess seed handling during the treating process by visually inspecting seeds, counting cracked seeds, or performing a final germination test

This can help inform your treatment process for next time. Make notes to help with remembering what to adjust next year!

For information about specific seed treatment products please contact your local Bayer SeedGrowth® representative or visit the website.

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