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Rehydrating and Pulsing

S.T.S. TREATMENT FOR CARNATIONS
Treatment with silver thiosulphate (S.T.S.) supplies the flower with silver ions which inhibit ethylene action and helps prevent "sleepiness" in carnations, Snapdragons, Delphinium, Gypsophila, Larkspur, Lissianthus, stock and many other crops. the following treatment is for carnation but can be used for many other crops. You can use it on other crops but always experiment on a small amount first.

Pulsating Treatment

  • Stand bunches in 2mm S.T.S. solution in plastic buckets for approximately 15 mins at room temperature.(Check that between 2.5 and 25 ml of solutions is taken up by a bunch of 10 stems during this time UNDER TREATMENT CONDITIONS).
  • 2.Transfer bunches to water or preservative solutions for at least on hour to allow silver to reach flower head.

Overnight Treatment

  • Stand bunches in 0.2mm S.T.S. solution in buckets and place in cold rooms. (Check that between 25 and 250 mls of solution is taken up by a bunch of 10 stems during the time flowers are left in the solution UNDER TREATMENT CONDITIONS).

NOTE: Solutions for overnight treatment are much less concentrated than those for pulsing. Uptake of solution is greater at warmer temperatures and if flowers are not put in water prior to treatment.



PREPARATION OF CONCENTRATE SOLUTIONS

  • Stock solutions should be stored in clean dark coloured plastic or glass containers away from bright light.
  • Accurate measurements are required.

Silver nitrate (Ag NO3)
To prepare 1 litre of solution add 17 grams of silver nitrate to 1 litre of water.

  • Use only distilled or deionised water or high quality tap water.
  • The solution should remain clear. Chlorine salts in the water will cause the solution to turn black and cloudy. The solution must be discarded if this happens.
  • Silver nitrate is a toxic chemical. The crystalline salt and concentrate solution will cause dark staining to the skin.

Sodium thiosulphate (Na2 S2 O3 5H2O)
To prepare 4 liters of sodium thiosulphate stock add 100 grams of sodium thiosulphate pentahydrate to 4 liters of water.

PREPARATION OF TREATMENT SOLUTIONS

  • Plastic buckets should be used. These must be clean and contain no residues of detergents or bleaches.
  • Never mix the stock solutions directly.

To prepare 10 litres of 2mm solution for 15 min pulse.

  • Place 9 000 ml of water into a 15 liter bucket.
  • Add 800 ml of sodium thiosulphate concentrate and stir.
  • While stirring vigorously slowly add 200 ml sliver nitrate concentrate.
To prepare 10 litres of 0.2 mm solution for 24 hr treatment.
  • Place 9 900 ml of water into a 15 liter bucket.
  • Add 80 ml of sodium thiosulphate concentrate and stir.
  • While stirring vigorously slowly add 20 ml of silver nitrare concentrate.
  • Clearly label buckets containing treatment solutions.
  • A depth of only 10 cm treatment solution is required.
  • Treatment solutions may be used for a few days before discarding.

GENERAL RULES FOR PREPARING S.T.S. TREATMENT SOLUTIONS

To make up 10 L of solution:
  • For every mm of silver in the treatment solution, 100 ml of silver nitrate stock is Required (ie 0.5 mm needs 50 ml, 4 mm needs 400 ml).
  • Four times as much sodium thiosulphate stock is required in each case.
  • The total volume (silver nitrate + sodium thiosulphate + water) must be 10 L, so the correct amount of water to use will differ between concentrates.
  • Always follow the order:
    • Measure water into bucket.
    • Add sodium thiosulphate stock + stir.
    • Stir while slowly adding silver nitrate stock.

* A table showing the correct amount of water and stock solutions to use to make up 10 L of treatment solution for a range of concentrations is shown below.