10 best practices for treating potato seed pieces

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The condition of a seed piece can have a significant effect on its ability to perform. That’s why it’s important to understand the physiological age, condition, disease spectrum and other characteristics of a specific batch of seed or a selected variety.

Keep these tips in mind when treating your seed pieces this spring.

BEFORE YOU TREAT

1. Prepare for your seed’s arrival.

   Before receiving your seed, all machinery, transport, and storage surfaces that will contact the seed pieces should be cleaned and disinfected with labelled products.

2. Check for sprouting in your seed pieces.

   All liquid potato seed treatment labels state treatments should not be applied to severely sprouted seed. Sprouts can break off during or after treatment, leaving an area of the seed piece untreated. And, since a broken sprout stub or other exposed area will not suberize like a cut tuber surface, the wound is more susceptible to disease.

3. Consider the physiological age of your seed.

   While dormancy and physiological age are considered separate issues, growth and storage conditions that influence physiological aging can also influence dormancy.

   Any condition that places the growing seed crop under stress causes physiological aging of the seed. Low moisture, high temperatures, inadequate fertility, frost damage and disease pressure may cause stress and consequently age the seed.

   Bruising increases the respiration of the seed, which also accelerates the aging process. (It can create an entry point for pathogens too.) It’s best to minimize any drop of seed – whether it’s whole or cut seed. A simple drop of more than 15 cm (six inches) is enough to create significant bruising in cut seed.

   Temperature matters too. Seed held in storage at a constant 3-4°C at 90 percent relative humidity will age slower than seed held at higher or fluctuating temperatures.

   Seed treatments do not affect the physiological condition of the seed.

4. Think about your disease spectrum.

   Agriculture and Agri-Food Canada research has found some Fusarium spp. resistance to fludioxonil and thiophanate-methyl in different potato growing areas across Canada. When selecting a seed piece treatment, consider the full spectrum of diseases in your region.

5. Conduct a batch test to better understand your seed.

   Seed will have inherent differences in how it heals. Performing a batch test on a sample of your seed is important to see how each seed variety and lot received on the farm responds to your selected seed treatment.

APPLYING YOUR SEED TREATMENT

For Syngenta liquid Seedcare™ products, we suggest using a recommended enclosed treater. This allows you to capitalize on your preferred application method and encourages thorough coverage through atomizers and seed to seed rubbing and cushioning during liquid seed treatment application.

For seed treatments from other manufacturers, consult the product label for treatment equipment recommendations.

6. Ensure the correct volume of slurry.

   When adding another component to the slurry, ensure it’s compatible and added in accordance with the labeled rates.

   Be sure to maintain labeled rates of products and recommended slurry volumes, and ensure good coverage on all of the seed being treated. Potatoes should be completely covered with no excess moisture.

7. Add an inert dust after liquid application.

   Use of an inert dust is one factor that may improve conditions for wound healing, or suberization. Inert dust may also improve conditions for suberization in varieties that are inherently low in specific gravity or ‘high water content’ seed, in higher humidity treating environments, and when planting into wetter soil conditions.

8. Encourage suberization.

   Suberization is a natural process that’s influenced by temperature, humidity, and the availability of oxygen. When a potato tuber is cut, it undergoes a three-stage wound-healing process. First, lignin, a woody polymer, is deposited between the cells. Next, suberin, a waxy polymer, is deposited over the exposed area. Lignin and suberin act as a first line of defense against infection and protect that area of the seed piece from drying out. The third step actually creates new kinds of cells, phellem, below the suberin. As these new cells begin to form, their starch is depleted and their cell walls thicken, resulting in brick-like layers of cells. Phellem is the final stage of wound-periderm formation. At the end of this stage, the “skin” is fully restored to its original protective capacity.

   You can also give your seed pieces a better opportunity for suberization by:

   • Calibrating knives – no more than two cut surfaces per seed piece
   • Conducting a batch test
   • Treating seed in temperatures >7ºC to avoid shatter
   • Using clean water
   • Disinfecting equipment from time to time using labeled disinfectant and allowing it to work for at least 15 minutes

   Soil conditions are also an important factor. Potato seed pieces need oxygen for healing in the soil. Hard pans in soil, or in and around the planting furrow, have very poor available oxygen and will slow the suberization process and increase the chance of seed decay due to poor wound healing. This problem is made worse when the soil is wet, poorly drained and less then °7C.  Liquid seed treatment cannot fix this problem. Ensure the soil is prepared well with air space around the seed piece and ideally, with complete absences of soil hard pan near the seed. Another factor that plays into suberization is the decision to store treated seed or to plant it right after treating.

STORING TREATED SEED

If conditions are favourable (dry sandy soil that is between 10-12°C), Syngenta recommends cutting, treating, and planting, however weather, equipment or operational issues may mean you need to cut, treat, and store seed instead.

Cutting and treating seed in advance allows you to plant when weather and soil conditions are optimal. Pre-cutting also allows cut seed to suberize prior to planting. However, it’s important to make sure seed is stored in a manner that allows proper suberization.

9. Limit the time seed spends in storage.

   Where conditions aren’t favourable for cutting, treating, and planting, seed can be stored for a reasonable period of time. Store the seed long enough to initiate wound healing (usually 3-4 days after treatment).  Storage for seven to 10 days will allow optimum performance. Do not store treated seed for more than two weeks.

   While seed pieces are in storage, aim to maintain temperatures of 10-11ºC and 80 to 90 percent relative humidity.

10. Ensure uniform air movement throughout the pile.

    Stored seed should be well ventilated, allowing approximately 0.5 cubic ft/minute of movement through every part of the pile. However, do not use air from a chlorpropham (CIPC) system or air from storages treated with CIPC to ventilate stored seed.

    Syngenta does not recommend storing seed in boxes unless you are familiar with the requirements to maintain proper air flow and the proper storage environment for your seed while using boxes.

    Do not store treated seed in trucks.

As you can see, there are a lot of factors to consider when treating potato seed pieces. The best course of action is always the one that takes a grower’s seed, operations, and the environment into consideration.