2018 Apple Maturity Assessments: Week Five

The Premier Honeycrisp harvest is ending as the Honeycrisp and Gala are maturing.
2018 Apple Maturity Assessments: Week Five - News

Updated: September 8, 2018

2018 Apple Maturity Assessments: Week Five

Color sorting Premier Honeycrisp apples in the laboratory for storage trials. Photo: Chris Walsh, University of Maryland

In addition to weekly reports on apple fruit maturity, this grower-supported project also tested the effects of pre-conditioning on the storage of Premier Honeycrisp and Honeycrisp apples. Pre-conditioning is a widely-used practice by Great Lakes, New York, New England, and Canadian apple growers to avoid “chilling injury” in stored Honeycrisp fruit. This is not a common practice in mid-Atlantic growers and we did not see typical chilling injury symptoms in our 2016 and 2017 storage trials. However, those were both hot, dry summers which may explain the lack of chilling injury.

A cool, wet season of 2014 led to storage losses from soggy breakdown. While 2018 was cool and wet, the recent 10-day heat wave may have also stressed the fruit. Since chilling injury tends to be associated with cool, wet growing seasons, 2018 may be a year where preconditioning could reduce soggy breakdown and soft scald in storage. Unfortunately, we do not have adequate data to make that a pre-storage recommendation.

Premier Honeycrisp

Harvest was slowed by wet weather in August, but most growers with Premier have now completed picking this variety. This a large-fruited variety and prone to pre-harvest drop. So growers who still have unharvested Premier Honeycrisp should be ready to pick, even if they have applied a stop-drop spray.

Gala and Honeycrisp

While August apples have been grown for centuries, early apple harvests dramatically increased when Gala began being planted widely in the 1990s. Although Gala is a small apple, its fruit flavor and heat tolerance made it a hit for apple growers. In Maryland, we've usually picked the original Galas (or Kidd’s D-8) about the same time as Loring peaches - between August 15th and August 25th.

Although Gala is a relatively heat-tolerant, it did not stand up well to hot, dry weather of the past two seasons. Last year, Galas progressed from immature to overripe in about ten days. While this was going on, Honeycrisp was also tree-ripening, which lead to a picking and marketing dilemma.

In this year's maturity trials, we started monitoring ReTain-treated Gala and Honeycrisp fruit grown in Maryland to provide maturity data before most growers reading this weekly report begin picking Gala and Honeycrisp. Sampling was done in a Central Maryland orchard located at 575 feet elevation. Fruit maturity there should be similar to maturity in southern Pennsylvania. The progression of fruit maturity from spot picked Gala and Honeycrisp fruit from that location is shown in Table 1 and Figures 1 and 2. As you see from that table, fruit maturity changed markedly during the past ten days. At the same time, we are again noticing that soluble solids are still low, measuring between 10 and 11 Brix.

As Gala acreage increased, the use of the ethylene synthesis inhibitor AVG, (the active ingredient in ReTain) also increased. When we harvested fruit in these blocks ten days ago, we saw no difference between treated and untreated fruit. Since then, differences in fruit size, color and maturity can be seen. We expect spot picking of the untreated Gala and Honeycrisp apple trees to begin soon, well before picking of the ReTain-treated fruit.

While these observations were taken from fruit grown on supported slender-spindle trees, be sure to check your fruit maturity as small differences in microclimate or orchard management may make a large difference in maturation and tree ripening. Summer management practices that might hasten fruit maturity are summer PGR applications to enhance return bloom, and mechanical pruning to increase red color development.

Table 1. The following table shows data from our pre-harvest samples taken in the same orchard block during the past three weeks. As you can see, harvest maturity data changed dramatically this week.

Honeycrisp: Central Maryland 575 feet elevation

CultivarDiameter (inches)Red Color (%)Ground ColorFirmness (pounds)Starch Pattern (1 – 8)Soluble Solids (°Brix)
10-Aug-1833Light green20.61.411.3
21-Aug-18
No ReTain350Yellowish green16.36.811.5
ReTain2.920Yellowish green16.34.710.6

Gala: Central Maryland 575 feet elevation

CultivarDiameter (inches)Red Color (%)Ground ColorFirmness (pounds)Starch Pattern (1 – 8)Soluble Solids (°Brix)
10-Aug-182.712.5Yellowish green19.9211
21-Aug-18
ReTain (1x)327Whitish yellow14.95.611.6
ReTain (2x)2.920Whitish yellow16.24.411.1

Honeycrisp: Adams County PA 1,200 feet elevation

CultivarDiameter (inches)Red Color (%)Ground ColorFirmness (pounds)Starch Pattern (1 – 8)Soluble Solids (°Brix)
14-Aug-18318Light green18.21.210.5

Figure 1. Honeycrisp apples spot picked in Central Maryland on August 21, 2018. The redder fruit shown on the left received no ReTain treatment (control), while fruit on the right were treated with ReTain. Photo: Audra Bissett, University of Maryland

Figure 2. Gala (Kidd’s D-8) apples spot picked in Central Maryland on August 21, 2018. The redder fruit shown on the left were treated with one half-rate spray of ReTain, and fruit shown on the right received two half-rate sprays of ReTain. Photo: Audra Bissett, University of Maryland

More Information

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