When to Harvest Your MN55 Apples for First Kiss® Quality

Sampling First Kiss® apples at Pine Tree Apple Orchard on Aug. 17, 2020. Photo: Annie Klodd.

I have enjoyed the opportunity to taste test First Kiss® apples from MN55 trees at Pine Tree Apple Orchard's Preston and White Bear Lake locations this week. The apples we tasted were just a few days away from harvest - sweet and crisp, but still too starchy to be picked. I also saw a photo of First Kiss® apples at a farmers' market last weekend that were harvested about a week too early and still had a green undercolor. So, this prompted a discussion with Dr. Jim Luby about when to harvest MN55.

Key Points for Harvesting MN55

Harvest parameters: 

1. 80-95% scarlet red overcolor
2. Undercolor starting to break from green to yellow
3. 14-19 lbs pressure
4. Starch iodine 5-6 on the Cornell scale
5. Brix 12-13
6. Acid 9-7 g/L or lower. 
7. Use these parameters to determine harvest timing; do not rely on color alone, or you will likely be harvesting overly tart fruit

Additional important harvest information:

1. Early maturing apple that is harvested between August 17-26 in Minnesota
2. Harvested 1-2 weeks before Minneiska (SweeTango® apples)
3. Colors quickly, just before maturity
4. Like many varieties, harvesting MN55 too early results in an overly tart, starchy apple
5. Typically requires 2-3 harvests. Anticipate and plan for 3 harvest dates.
6. Wait to harvest until a majority of the fruit meet the harvest parameters listed above. Otherwise, pickers may end up picking fruit based on color that is not yet ripe.

MN55 is highly susceptible to fruit drop prior to maturity. University of Minnesota recommends applying stop-drop sprays (NAA/Fruitone or Retain) in the two weeks leading up to harvest

Stop-drop sprays:

Most of the time frame for applying stop-drop sprays for MN55 has passed, since harvest will likely start this weekend. However, growers may need to do one more application of NAA (Fruitone) if the harvest is prolonged. For future reference, NAA (Fruitone) and aminoethoxyvinylglycine (ReTain) are the two options for stop-drop sprays described below. Unfortunately, neither of these products are approved for use in certified organic orchards.

Fruitone (NAA) recommendations: Apply according to label directions 7-10 days before anticipated harvest. It starts being effective two days after application, and remains effective for 7-10 days. A second application closer to harvest may be needed if drop is observed or if more than 8-10 days have passed and not all of the fruit have been harvested yet. Since it can stimulate ripening, do not use it on overripe fruit. 

ReTain recommendations: Apply according to label directions, in one application. Apply a 1/2 rate two weeks before the anticipated harvest. No second application should be needed.

Using Fruitone and ReTain together: Apply a tank mix containing a 1/2 rate of Retain and 20 ppm of Fruitone 7-10 days before harvest. Only one application is needed. This application may slow down fruit ripening and color development. 

For more information on First Kiss®and Rave®, along with all other University of Minnesota releases, visit mnhardy.umn.edu. 

Author: Annie Klodd, UMN Extension Educator – Fruit Production. Kloddann@umn.edu.  Recommendations courtesy of David Bedford and Jim Luby, UMN Fruit Breeding Program