Recent weather helps with apple maturity
A week of excellent weather increased coloration and maturity of Michigan apples. Growers should consider appropriate handling and storage conditions to preserve this wonderful apple quality.
This past week (as of Oct. 1, 2014) brought us excellent weather for advancing the coloration and maturity of all our apple cultivars. In the Sparta, Michigan area, even Cripps Pink (also known as Pink Lady), a variety so late it never properly ripens here in Michigan, has seen some color formation. In my 25 years as a post-harvest physiologist, I cannot recall better color.
As noted in a previous apple maturity report from Michigan State University Extension, it has been a cool year, somewhat similar to 2009. In that year, we found controlled atmosphere (CA) injury prevalent in our Honeycrisp if the fruit were not conditioned properly and plunged directly into a CA containing 3 percent O2 and 3 percent CO2. Chris Watkins of Cornell University also notes in the Harvest Maturity Report by Craig Kahlke for this week that a cool season is linked to an increased susceptibility to a number of internal browning disorders, including chilling injury. In fact, there has been at least one report of some chilling injury in Honeycrisp from a Grand Rapids, Michigan area orchard already.
This should serve to put our industry on alert for using appropriate handling and storage conditions to preserve the quality of our beautiful and bountiful crop. An article in the forthcoming NY Quarterly, “Toward Optimizing CA Storage of Honeycrisp Apples: Minimizing Prestorage Conditioning Time and Temperature,” will help describe some of the alternatives for Honeycrisp. Also, it is worth noting that in our ongoing laboratory experiments, we have already begun to find CA injury in Honeycrisp that have been stored in CA (3 percent O2 with 3 percent CO2) without conditioning or diphenylamine (DPA) treatment.
I looked back over my records for the maturation of apples in 2009, a year with very similar (low) growing degree day accumulation, and found similar delay in the maturation of our early varieties. For instance, Gala harvested from the Sparta, Michigan area in 2009 had only just begun to ripen by the third week in September and well underway by the fourth week, which is very similar to this year (although color is better in 2014). In contrast, Gala fruit, if you had them, were rapidly ripening by Sept. 4 in 2012 and Sept. 2 in 2010! Interestingly, Honeycrisp ripening trailed Gala considerably in the warm years, but was well ahead of Gala in the cooler years, probably by seven days or so.
Finally, with advancing cool and rainy weather, it will be important to make as much progress as possible in getting fruit out of the orchard and into our storages. Keep in mind that apple fruit store best if they have not yet begun to produce ethylene (and they will taste pretty “green”), and that CA and SmartFresh are most beneficial on fruit harvested at this stage. Balancing harvest maturity with storage duration continues to be important despite our technological options (CA, ReTain and SmartFresh) for improving maintenance of fruit condition.
Dr. Beaudry’s work is funded in part by MSU‘s AgBioResearch.