MSU Extension Apples

This is the ninth apple maturity report for the 2021 harvest season. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

For general information about how samples are collected and processed, please refer to Apple Maturity Report #1.

• Considerations for the 2021 harvest season can be found in this article.
• More information on harvest management tools and timings can be found in this article.
• Guidelines from MSU to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety.
• Predicting apple maturity and starch chart from Cornell University
• Starch chart for Honeycrisp Apples developed by Washington State University.

How to read the maturity tables

For each variety evaluated, we provide data from our evaluations in a table. In each, a row is provided for each sample tested. This allows you to see how the varieties may be progressing in different regions or specific locations. An average is included for each variety. Maximum and minimum values are included for the highest and lowest individual fruits evaluated for each, to give a full spectrum of the maturity. Recommended values are included for each variety at the bottom of the table. These suggested values for firmness and starch index were also published in a standalone table format. Firmness ranges encompass long and short-term storage recommendations.

Updates for this week

• Harvest is moving along very quickly. Most growers expect to finish harvest much earlier than usual. This is a result of the lighter crop this year and earlier maturity this season.
• Conditions have been warmer than normal over the past week. This is expected to continue over the next week, with highs in the 70s degrees Fahrenheit and lows mostly remaining in the 50-60s. This is less than ideal for red color development.
• There is considerable variability in maturity and quality for many varieties due to the extended bloom, warm season and ample rainfall this season.
  • Overall, fruit is softer and more mature this year than it has been in the previous two years.
  • Fruit going into bins may be a wide range of quality, which will have important impacts on storage.
  • It will be critical to do everything possible to ensure optimum storage conditions. This includes cooling fruit quickly and treatment with 1-MCP.
  • Randy Beaudry wrote a summary of the conditions and considerations to take into account for this year.
• Golden Delicious, Mutsu and Idared untreated fruit have been harvested or will be in the next week.
• Red Delicious are moving quickly and harvesting this week in most locations.
• Ambrosia are harvesting now.
• Fuji are showing signs of maturity and should begin harvest next week.
• Evercrisp are showing signs of maturity and should begin harvest in a couple of weeks.
• Rome and Braeburn varieties are still immature but showing increasing signs of ripening.

Golden Delicious

This variety has been harvested in most locations or should be harvested now. Color has improved from green to yellow in most location and size is very good. Minimal red color was observed, with only a touch of blush on a few fruits. Starch clearing, firmness and sugars all indicate fruit is very mature. Our predicted harvest date for Goldens was Oct. 1 and most fruit were mature by then.

Golden Delicious sampled Oct. 4

Golden Delicious weekly averages

Red Delicious

This variety is maturing quickly and harvesting in many locations this week. Ethylene development is evident in many samples with some over the 0.2 ppm climacteric. Pressures have decreased this week. Typically, we like to see pressure of about 15 pounds at the consumer end, and fruit harvested at this pressure are beyond the appropriate condition for long term CA storage. Model predicted harvest was Oct. 7 for this variety but we expect actual harvest to be slightly earlier.

Red Delicious sampled Oct. 4

Red Delicious weekly averages

Idared

This variety is harvesting this week in most locations. Model predicted harvest was Oct. 7, but we expect actual harvest to be slightly earlier.

Idared sampled Oct. 4

Idared weekly averages

Ambrosia

Ambrosia is still a new variety for the area, and we are learning about maturity for our region. Internal qualities indicate fruit is ready for harvest. Color is variable; it is still less than excellent in some places and other locations there is nice bright red development. It appears to be a heavy ethylene producing apple, with many fruit producing significant amounts in our sample last week and again this week. Starch clearing is difficult to interpret, with an interesting mosaic pattern. Clearing appears to begin throughout the flesh even while some of the cortex is still not clear.

Overall, this variety needs a little more time for red color development if possible. In some areas, internal qualities indicate the fruit are ready for harvest. In other areas that grow Ambrosia, they pick it about the same time as Red Delicious.

Ambrosia sampled Oct. 4

Ambrosia weekly averages

Rome

Overall, Rome is still a little immature. Color is developing nicely but firmness, sugars, and starch indicate it still needs a bit more time. Model predicted harvest was Oct. 14, and we anticipate it to be close to accurate but like everything else this season, they might come in slightly earlier. There was no color bleeding in any of the Romes we sampled.

Rome sampled Oct. 4

Rome weekly averages

Fuji

Fuji is showing signs of ripening and should be watched closely. Color is much improved from last week, but still developing. Pressures are still somewhat high, and starch is continuing to clear. Watercore was observed in a number of fruits this week but was relatively minor. Randy Beaudry reminds us each year that this variety is typically mature right after Red Delicious, and that we often wait a little longer than probably necessary to harvest, typically while waiting for color development. This variety does not stain well with iodine, and starch pattern fades quickly. Internal ethylene is being produced in several fruits. Model-predicted harvest was Oct. 20, but we anticipate actual harvest date to be considerably earlier, especially if color improves.

Fuji sampled Oct. 4

Fuji weekly averages

Evercrisp

Overall, Evercrisp is still somewhat immature. A little more red color development has taken place, but more is necessary and background color is very green. This is a high ethylene producing variety, which was detected in all samples. Starch clearing is just beginning. Soluble solids are high, which is a contribution of the Fuji background.

Evercrisp sampled Oct. 4

Evercrisp weekly averages

Braeburn

Overall, Braeburn is still immature. Fruit is very firm, low in sugars and starch clearing is continuing.

Braeburn sampled Oct. 4

Braeburn weekly averages

Apple maturity sampling parameters

• % fruits with internal ethylene over 0.2 ppm = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested
• Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
• Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
• Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
• Brix = % sugar measured with Atago PAL-1 Pocket Refractometer

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.