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What is the correct carbon dioxide concentration?

Dr. Prange did a recent presentation on the management of

CO2 levels in apple and pear CA storage. Watch the presentation here:

Key Summary:

– Too much CO2 can cause external and internal fruit damage.

– Avoiding CO2 damage will depend on: Cultivar, Oxygen concentration, Stage in

storage season, Storage temperature, Storage humidity, Use of post-harvest

chemicals – 1-MCP, DPA.

– Timing Matters: High CO2 at the beginning of storage is more damaging than later in


– Post-harvest chemical influence: The CO2/O2 ratio in CA is lower if 1-MCP is used

while DPA can reduce CO2 damage.

Final Considerations:

– If no history of CO2 damage – maintain current practices.

– If there is a history of CO2 damage, consider one or more of the following:

o Scrub CO2 during loading and cooling, e.g., activated carbon and/or lime

o Scrub CO2 during O2 pull-down.

o In CA, control CO2 levels according to the CO2/O2 ratio for a specific cultivar.

o Consider scrubbing CO2 for the first few weeks of CA. i.e. 4 weeks.

o There is evidence that cultivars that tolerate high CO2/O2 ratios may lose

their CO2 tolerance at chilling temperatures, i.e., < 1.0 ºC.

o In DCA (<1 kPa O2), there is evidence that the CO2/O2 ratio can be higher.

o If 1-MCP is applied at beginning of storage – reduce CO2 by ca. 50%

o If DPA is allowed – it may reduce risk of CO2 damage

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