Root Media Pasteurization

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Chapter 6

• Root Media Pasteurization

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DEFINE

• Pasteurization
• Sterilization
• Commercially Sterile
• (We will use the above terms interchangeably)

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Uses of Pasteurization

• Basically only when
• Ground beds are used
• Media is reused
• Native soil is used

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Two types of Sterilization

• Steam
• Media heated to 140-160 oF for 30 min.
• (Timers starts when coldest spot reaches 140o)
• 140o kills most pathogenic bacteria
• (Some weed seeds viruses may survive)
• 160o kills all
• Media must be loose moist
• Uses perforated pipe under media to deliver steam

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• Chemicals
• Advantages
• Cheaper than steam
• Can be used where steam
• pipes are not buried
• Disadvantages
• Up to 10 day wait to use media
• Human hazard during application
• Methyl Bromide w/ 2 chloropicrin is most common
  chemical used (kills everything) - Must be tarped
  w/ plastic

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