Storage Workshop Key Takeaways

Mike Basedow and Dan Donahue, CCE Eastern NY Commercial Horticulture

We both attended the storage workshop in Ithaca on August 8th, and thought we would share the main takeaways. We've included some recent recommendations for Honeycrisp, Gala, NY-1, NY-2, Mac, Cortland, and Empire, along with a quick comparison of utilizing dynamic controlled atmosphere (DCA) storage and 1-MCP.

Honeycrisp. For fruit stored in air, fruit should be stored at 38°F, with or without conditioning for 7 days at 50°F. Conditioning Honeycrisp will help reduce soft scald, but will likely exacerbate bitter pit. The decision to condition or not should be determined by your block history. If a block is very vulnerable to bitter pit, it is likely best to skip conditioning. However, if you rarely get bitter pit and often have issues with soft scald, conditioning would be warranted. Air stored fruit can be treated with 1-MCP, as it will help fruit retain acceptable levels of acidity. 1-MCP may also increase core breakdown, but may decrease the incidence of bitter pit and senescent breakdown. An increasing number of growers are using Harvista to manage their Honeycrisp harvest. Chris's recent work found that Harvista decreased soft scald, but increased bitter pit incidence on stored fruit. Fruit treated with a combination of Harvista and 1-MCP also had a greater incidence of leather blotch. For fruit destined for CA storage, CO2 injury can be problematic, and is generally worse further south in the state. CO2 injury can be controlled with diphenylamine (DPA), or by delaying CA storage by up to 4 weeks. In Chris's studies, fruit that were delayed CA storage for up to 4 weeks and treated with 1-MCP had very little loss of fruit quality, but greasiness and core browning did increase to a small extent. The overall recommendation for Honeycrisp currently is air storage with 1-MCP to avoid CA related injuries.

Gala. A major concern for Gala right now is stem end flesh browning (SEFB).

So far we know that:

·Harvista decreases the incidence of SEFB.

·CA in general is very helpful for maintain Gala quality, though differing the values of CO2 concentration in CA storage showed inconsistent effects on SEFB.

·DCA at .5% O2 will help to further delay browning development, but will not completely prevent it. DCA may also prevent core browning.

·1-MCP in storage appears to not have an effect on SEFB. Washington State and Ontario studies suggest delayed cooling, paired with early CA storage, may help to reduce some browning disorders. This approach needs more study in New York conditions.

Regardless of storage treatment, being on top of harvest date (erring earlier than later) and planting high-coloring strains like Brookfield that can be picked earlier are two of the best strategies for successful long-term storage of Gala.

NY-1. For successful long-term CA storage of NY-1, the current recommendation is to focus on your harvest management. NY-1 should be picked as early as possible to avoid fruit with high internal ethylene, though this may require compromising between ethylene and fruit color. Fruit should be stored at 38°F like Honeycrisp to reduce stem end flesh browning. Chris does not currently recommend 1-MCP for NY-1, as it aggravated flesh browning in his CA storage trial.

NY-2. Similar to NY-1, Chris suggests early harvest timing is key to maintaining good quality for long term CA storage. NY-2 should also be stored at 38°F. 1-MCP is recommended for NY-2. In Chris's studies, 1-MCP helped retain firmness, and reduced superficial scald and stem end flesh browning. It did, however, lead to some additional general flesh browning. Some of Chris's future work will determine how NY-1 and NY-2 respond to DCA storage and harvest management PGR's.

McIntosh. 1-MCP helps keep macs firm on the shelf after long-term storage, and will also help reduce superficial scald and senescent breakdown. It may, however, slightly increase CO2injury. DCA storage can be used in macs to reduce CO2injury.

Cortland are hard to control against superficial scald regardless of postharvest treatments, but both DCA and 1-MCP help to some extent. DCA plus 1-MCP returned the best fruit in Chris's trials, but the added expense might not make this approach feasible commercially. DCA helps maintain fruit quality regardless of 1-MCP treatment, but a tasting panel found that Cortland stored with 1-MCP maintained a better level of ‘snap' after storage.

1-MCP treated Empire tend to retain their firmness better, but these may pick up more CO2injury and flesh browning. For Empire flesh browning, the best way to keep levels down is to harvest at proper maturity. Later picks will pick up more browning, regardless of 1-MCP or DCA practices.

How does DCA stack up to 1-MCP? Dynamic controlled atmosphere (DCA) is a storage method that actively measures fruit response to storage oxygen levels to determine the optimum oxygen level for that storage room. By keeping the oxygen level just above the "low oxygen limit", respiration rate can be reduced to a minimum. By slowing respiration further, fruit quality out of DCA storage is higher, with less superficial scald. Below are some of the benefits (+) and negatives (-) of using DCA and 1-MCP.

DCA:

• Chemical Free
• Easily installed in existing high quality storages
• Can inhibit superficial scald and some internal flesh browning disorders
• Need to have that high quality facility-Higher upfront investment costs
• Need to select uniform fruit to serve as your samples
• Requires training of storage operator to interpret fruit responses to O2levels
• Greater potential for quality loss after storage, unless combined with 1-MCP1-MCP
• Applied as a gas at low concentrations for 24 hours or less
• High quality rooms not required
• No investment on computerized CA technology
• No risk of low O2injury
• Flexible timing of 1-MCP application
• Can maintain fruit quality in air storage
• Can inhibit superficial scald development
• Maintains quality parameters, like firmness and acidity, during the marketing chain
• Not for organic use
• Ongoing cost every time you apply
• Can increase some physiological disorders, like CO2injury.