MSU Extension Apples

This is the eighth 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

Weather – In the Grand Rapids, Michigan, area, harvest is moving along quickly! Weather has been beautiful. Aside from a few rainy days last week, conditions have been clear, sunny and temperatures very moderate.

Maturity in many varieties is advancing very quickly. We are seeing many varieties entering harvest windows slightly earlier than predicted harvest dates. It is very important to be testing fruit earlier than normal to detect fruit that is maturing ahead of expected targets.

Jonagold and Empire untreated fruit have been harvested or will be in the next week.

Golden Delicious is ready for harvest now.

Red Delicious is moving quickly and should begin harvest very soon for long term storage. Considerably earlier than predicted harvest date.

Ida Red maturity is moving quickly, should be picked in the next week.

Ambrosia internal qualities show fruit are mature, but color is less than excellent in some locations. Harvesting now.

Evercrisp, Fuji, Rome and Braeburn are still immature, but showing increasing signs of ripening.

Predicted harvest dates according to the Maturity Model in Enviroweather are approximately normal or slightly early for later varieties. At this time, the season appears to be a few days ahead of normal.

Mixed maturity is evident in most varieties and locations. Multiple picks may be needed to harvest fruit at the appropriate maturity for successful storage conditions.

Empire

This variety has been harvested in most locations. Model-predicted harvest date was Sept. 22 for this variety and they seem to be coming in right on target. Fruit treated with AVG or 1-MCP is delayed as expected.

Empire sampled Sept. 29

Empire weekly averages

Jonagold

The harvest window is beginning to open for Jonagold for fresh market. Color is less than excellent in most places, although a few locations or fruit at the end of rows are coloring nicely. Background color is changing from green to yellow noticeably. Harvest is expected to begin for most locations in the next week to 10 days. Model predicted harvest was Oct. 1, but we expect actual harvest to be slightly earlier where color is adequate and crop load is light.

Jonagold sampled Sept. 29

Jonagold weekly averages

Golden Delicious

This variety 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 fruit. Evaluation of starch clearing, firmness, and sugars all indicate fruit is mature. Flavor of fruit is also showing noticeable development. Our predicted harvest date for Goldens was Oct. 1 and that date seems to be a bit on the late side according to the fruit we are testing. Many Golden blocks have a light crop load and are ripening faster than expected.

Golden Delicious sampled Sept. 29

Golden Delicious weekly averages

Red Delicious

This variety is maturing quickly and has entered the window for long term CA storage in most locations. Ethylene development is evident in many samples with some over the 0.2 ppm climacteric. Pressures, starch, and sugars are just entering acceptable harvest ranges. Model predicted harvest was Oct. 7 for this variety but we expect actual harvest to be slightly earlier.

Red Delicious sampled Sept. 29

Red Delicious weekly averages

Idared

This variety is showing signs of maturity and just beginning to enter the harvest window. Model predicted harvest was Oct. 7, but we expect actual harvest to be slightly earlier.

Idared sampled Sept. 29

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 very near or 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 Sept. 29

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 Sept. 29

Rome weekly averages

Fuji

Overall, Fuji is still somewhat immature, but should be watched closely. Color is still developing, pressures are high, and starch is continuing to clear. 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 a number of fruit. Our predicted harvest date is Oct. 20, but we anticipate actual harvest date to be considerably earlier – especially if color improves.

Fuji sampled Sept. 29

Fuji weekly averages

Evercrisp

Overall, Evercrisp is still very 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 likely a contribution of the Fuji parentage.

Evercrisp sampled Sept. 29

Evercrisp weekly averages

Braeburn

One sample was taken this week of this variety. Overall, Braeburn is still very immature. Fruit is very firm, low in sugars and starch clearing is just beginning.

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.