Northwest Michigan apple maturity report – September 20, 2023
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EmailHoneycrisp harvest has begun across northwest Michigan. There is variability in firmness and brix levels, likely due in part to excess rain in some regions and no rain in other areas.
This is the third apple maturity report for 2023 for northwest Michigan. Reports are sent out every week (usually on Wednesdays) following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.
Honeycrisp harvest has just begun in earnest this week. Premier Honeycrisp harvest is over as is Ginger Gold. Most other early varieties have also wrapped up. From our past testing, starch removal readings have been high while brix has lagged. Growers have also been waiting on color to improve before starting harvest. The recent cooler nighttime temperatures and these sunny fall days should help to advance color. Firmness is also a bit more variable from testing apples in regions that had excess rainfall on Sept. 6 (6-plus inches) compared to other areas of northwest Michigan that received less than a quarter inch of rain.
Weather
After a bit of a cool spell last week, daytime temperatures have crept up into the 70s degrees Fahrenheit, and the forecast is predicting mid-70s for the remainder of the week into the weekend with little to no rain in the predictions. The warmest days of the week will be tomorrow and Friday, Sept. 21 and 22, where the forecast is predicting high 70s and into the 80s. Nighttime temperatures will be cooler but down in the mid- to high 50s. We did have a cold night on Monday into Tuesday morning, Sept. 18-19, and the Northwest Michigan Horticulture Research Center recorded a low of 46.5 F, but other stations/grower orchards recorded temperatures as low as 38-40 F.
How to read maturity tables
Each week, we test apple varieties that are nearing maturity in northwest Michigan. We are reporting average values for several samples 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 maturity. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted.
- Predicted apple harvest dates for 2023 from MSU
- 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.
Honeycrisp
This important variety has begun harvest this week. Growers across the region have started to do first picks of Honeycrisp. As noted in past weeks, the starch removal measurements have shown this variety to be mature; however, brix levels and color were lacking. Growers have been waiting on color improvement and increases in brix before jumping into harvest. This unusual relationship between brix and starch removal is a bit of a mystery this season. We have noted some differences in areas where we received variable rainfall amounts, but this potential hypothesis does not hold up across all blocks we have been testing this week. MSU professor Randy Beaudry is interested in better understanding water and temperature relationships in this variety. Notably, southwest Michigan is still harvesting Honeycrisp this week and the Ridge area still has a few blocks to finish but mostly have moved on to Gala. Northwest Michigan is starting harvest, so the whole state is into Honeycrisp at an overlapping harvest window.
The average of our starch removal readings varies from 4-8 with an average of mature at 6.5. Interestingly, we have three samples from the Northwest Michigan Horticulture Research Center, and they all vary in their readings. Again, brix averages have not changed since we started testing for brix on Sept. 5. The ranges are also similar between the last three weeks of testing. Color has improved, and this week, we measured color to be 73% while last week and the week before were in the low 60s. Firmness remains high in all Honeycrisp tested, but we did note “eating” differences in firmness in blocks where there was excess rain compared to areas with no or little rain.
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Honeycrisp maturity sampling for the harvest season |
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Sample date |
Color % (range) |
Firmness lbs. (range) |
Starch (range) |
Brix % |
|
Sept. 5, 2023 |
60.2% (20-95) |
18.3 (15-22) |
3.8 (1-7) |
11.5 (8.8-14.3) |
|
Sept. 12, 2023 |
61% (10-95) |
17.7 (14-22) |
5.2 (2-8) |
11.5 (9.5 - 13.9) |
|
Sept. 19, 2023 |
73.1% (50-95) |
17.5 (14-23) |
6.5 (4-8) |
11.6 (9.3-14.3) |
Gala
Gala has matured since last week, and brix levels jumped almost 1.5% in our brix averages. Color has improved by over 10% since last week as well. Starch removal readings also increased to an average of 3.3, but the starch still have quite a range across the different blocks: 2-7. The background color of Gala has become more yellow this week, and size is variable across blocks with and without irrigation. Growers will be concentrating on Honeycrisp this week before moving into Gala blocks.
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Gala maturity sampling for the harvest season |
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Sample date |
Color % (range) |
Firmness lbs. (range) |
Starch (range) |
Brix % |
|
Sept. 5, 2023 |
72% (5-100) |
21.8 (19-23) |
1.4 (1-2) |
10.6 (8.6-13.6) |
|
Sept. 12, 2023 |
80.5% (30-100) |
20.4 (17-21) |
2.4 (1-6) |
10.6 (8.6-13.7) |
|
Sept. 19, 2023 |
92.3% (70-100) |
21.1 (17.5-23) |
3.3 (2-7) |
12.1 (9.1-14.8) |
McIntosh
We only tested one sample of McIntosh this week as the other orchards have already been harvested. In the single sample, the starch removal was 5.8 and the brix was 11%. Brix has not changed much in this variety over the past three weeks. On Sept. 5 and 12, the average brix was 10.5%, and this week only jumped a half of a percentage point.
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McIntosh maturity sampling for the harvest season |
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Sample date |
Color % (range) |
Firmness lbs. (range) |
Starch (range) |
Brix % |
|
Sept. 5, 2023 |
75.8% (20-100) |
18.6 (15-23) |
1.8 (1-3) |
10.5 (9.7-11.9) |
|
Sept. 12, 2023 |
79.8% (40-100) |
17.4 (14.5-21) |
2.8 (1-5) |
10.7 (9.2-12.6) |
|
Sept. 19, 2023 |
79% (only one sample) |
17.3 |
5.8 |
11.0 |
Apple maturity sampling parameters
- Ethylene (% 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. Indicates surface area covered in red and intensity of red color.
- 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.
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Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety. |
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Variety |
Firmness (pounds)* |
Starch Index* |
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|
Short CA |
Mid-CA |
Long CA |
Mature |
Over mature |
|
|
McIntosh |
14 |
15 |
16 |
5 |
7 |
|
Gala |
16 |
17 |
18 |
3 |
6 |
|
Honeycrisp |
15 |
16 |
17 |
3.5 |
6 |
|
Empire |
14 |
15 |
16 |
3.5 |
6 |
|
Early Fuji |
16 |
17 |
18 |
3 |
7 |
|
Jonagold |
15 |
16 |
17 |
3.5 |
5.5 |
|
Jonathan |
14 |
15 |
16 |
3.5 |
5.5 |
|
Golden Delicious |
15 |
16 |
17 |
3 |
6.5 |
|
Red Delicious |
16 |
17 |
18 |
2.5 |
6 |
|
Idared |
14 |
15 |
16 |
3.5 |
6 |
|
Fuji |
16 |
17 |
18 |
3 |
7 |
|
Rome |
15 |
16 |
18 |
3 |
5.5 |
