Spot picking fruit at the optimum stage of maturity, compared to slightly immature, can reduce bitter pit, whereas soft scald and soggy breakdown can be reduced by harvesting fruit before it becomes over-mature.
With support from Pennsylvania growers and packers, we have been conducting research the past three years that provides some guidance for harvesting this temperamental cultivar.
Following the 2014 harvest season, growers from regions around the state reported excellent Honeycrisp fruit quality - in some cases, the best they had ever seen. But several months following storage, a number of disorders started to appear.
Ben Rice, of Rice Fruit Company, calculated that 2014 packouts were reduced by an average of 17% for soggy breakdown, 8% for bitter pit and 3% due to senescent breakdown, for a total of $2.8 million in losses. Other packers reported similar percent losses, with fruit rots being an additional concern. Soggy breakdown is a chilling injury like soft scald and is likely associated with the cooler than normal harvest season.
Bitter pit observed on PA fruit in 2014. Photo courtesy of Yosef Al Shoffe, Cornell University.
Senescent breakdown observed on PA fruit in 2014. Photo courtesy of Yosef Al Shoffe, Cornell University.
Harvesting Fruit at the Optimum Stage of Maturity
The Honeycrisp Multiple Harvest Calculatoris a spreadsheet tool to help you assess whether increasing the number of times you harvest Honeycrisp will be cost-effective based on potential reductions in premature fruit drop and bitter pit is now posted at the Penn State Extension website. Sample increases in packout are based on our 2014 storage trials conducted on fruit segregated by background color following commercial harvest. Fruit from three different growers were segregated into three treatments:
- Fruit harvested with a background color that was slightly too green
- Fruit harvested at the optimum ground color of very light green to light yellow
- Fruit harvested with a deeper yellow background color
These fruit were then stored for 4 months at 38°F and evaluated for the incidence of storage disorders.
Fruit harvested slightly immature, or 3 versus 5 times, had 60% more bitter pit. Fruit harvested at an overmature stage, had 40% more soft scald.
Senescent breakdown, soggy breakdown and soft scald are more prevalent when fruit are harvested when over-mature. While red color development is desirable, it is important to also consider potential losses to chilling injuries and senescent breakdown.
Assessing Which Honeycrisp Apples are Ready to Spot Pick
A recent issue of Massachusetts Fruit Notes has a ground color chart that Duane Greene and Jon Clements found to be useful when harvesting Honeycrisp. The authors reported that when starch readings average about 6 on the Cornell starch-iodine index you should begin spot picking Honeycrisp, selecting fruit that have a background color of light green, white or light yellow and a pink blush turning to red.
Figure 1. Ground color chart (originally developed for McIntosh) that Greene et al. found to be a useful indicator for spot picking Honeycrisp (Cornell Extension bulletin 750).
Harvesting Honeycrisp at Optimum Maturity also Increases Consumer Acceptance
Another important reason for harvesting Honeycrisp at the proper stage of maturity is that prior sensory evaluation trials on PA fruit determined that consumers can readily detect the inferiority of apples harvested immature (Baugher et al., 2010). Consumers found fruit from heavily or lightly cropped trees to also be inferior in taste.
Photo: Fruit spot-picked at three stages (left to right - slightly immature, mature, slightly overmature) for taste tests conducted by a sensory evaluation panel.
100 panelists participated in this study conducted at the Penn State Sensory Evaluation Laboratory.
Average taste rankings for fruit harvested at three different stages of maturity based on background color. Ranking scale: 1-3, with 1 being most preferred.
(based on background color)
Increasing Calcium Levels in Fruit Relative to Nitrogen, Potassium and Magnesium
When you complete the final spray in your season-long calcium program, you should have applied a total of 9 to 14 lbs of actual calcium to your trees in order to influence both bitter pit and storage life. Recent research comparing calcium materials confirmed that these higher levels of elemental calcium are more efficacious on Honeycrisp (Greg Peck and Alan Biggs, 2015). Rob Crassweller and Lynn Kime developed a useful on-line spreadsheetto help with this calculation.
In our 2014 Honeycrisp research in commercial orchards, bitter pit was reduced when the level of calcium was high relative to nitrogen, potassium and magnesium. There was an interaction with crop load, with bitter pit further reduced at moderate crop loads.
Example of the increase in bitter pit with higher levels of potassium relative to calcium (from 2014 research in six commercial Honeycrisp Orchards).
Visual appearance of fruit harvested from trees with low (left), moderate (middle), and heavy (right) crop loads. Photo courtesy of J. Schupp.
Stem-Clipping to Increase Packouts
New York growers have more experience than we do with stem clipping fruit to prevent stem punctures and subsequent fruit decay. Growers and packers report a 5% reduction in decay with stem-clipping, and Lynn Kime developed the Honeycrisp Stem-Clipping Calculatorspreadsheet calculator to help you determine if this practice is cost-effective in your operation.
Research on Honeycrisp Continues
Our research on Honeycrisp continues this season. In addition to conducting additional field trials, we are cooperating with Chris Watkins, Cornell University, on a third year of storage studies with PA fruit. Chris was the featured speaker at a special Honeycrisp Symposium held the opening day of the 2016 Mid-Atlantic Fruit and Vegetable Convention.
- State Horticultural Association of Pennsylvania Research Committee
- Pennsylvania Department of Agriculture
- Christopher Watkins (Cornell University Post-Harvest Physiologist)
- Tom Jarvinen, Tom Kon, Edwin Winzeler, Melanie Schupp (Penn State)
- Lee Showalter, Leighton Rice, David Rice, Ben Rice (Rice Fruit Company)
- Ben and Joe Lerew, Dave Benner, Bill Lory, Chris Baugher, Dave and John Wenk, Jim Lott, Mark Rice, Dave Slaybaugh