Southwest Michigan apple maturity report – September 6, 2023
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EmailHoneycrisp and Gala apple varieties are maturing quickly in 2023 in southwest Michigan.
This is our weekly southwest region apple maturity report. Reports are sent out following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning. View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.
Report overview
Tests this week reveal that apples are maturing rapidly and some varieties appear to be ahead of the Michigan State University predictions for 2023. Reports for individual varieties tested this week are as follows.
Gala (Standard)
Internal starch conversion of this variety jumped between last and this week, with all sites considered mature now (3 or above for the starch test). This agrees with the predicted harvest date of Sept. 2. Fruit firmness averaged 18.2 pounds this week, compared to 18.6 for last week, suitable for apples going into long-term controlled atmosphere storage. Brix increased by 1.3 to an average of 11.5, still not flavorful.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 29 |
62 (60-65) |
18.6 (17.3-20.0) |
2.1 (1-3.2) |
10.2 (9.7-11.2) |
|
Sept. 5 |
87 (60-98) |
18.2 (16.8-18.8) |
6.2 (5-7) |
11.5 (10.8-11.9) |
*Starch values according to the 1-8 scale developed by Cornell University.
McIntosh
Strains tested include Ruby and Linda Mac. Starch indices average 4.8 this week, close to the mature threshold of 5. Fruit firmness is averaging 13.7 pounds, in the mid-range storage category. The predicted harvest date for central Berrien County in 2023 of Sept. 4. Most of the Macs have been harvested, some for applesauce.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 29 |
45 (20-60) |
14.9 (14.3-15.2) |
3.4 (3-4) |
12.0 (10.8-12.9) |
|
Sept. 5 |
70 (40-99) |
13.7 (13.4-14.0) |
4.8 (4.4-5.2) |
13.0 (12.3-13.7) |
Honeycrisp (Standard)
This variety is testing mature with starch index of 5.8, above the mature threshold of 3.5, and firmness averaging 15.6 pounds which is already in the midterm, controlled atmosphere storage range. This variety is maturing ahead of the predicted peak harvest date of Sept. 7.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sept. 5 |
56.5 (30-90) |
15.6 (14.8-17.1) |
5.8 (4.4-6.6) |
12.1 (11.3-13.1) |
*Starch values according to the 1-8 scale developed by Cornell University.
Empire
Much of the area Empire crop has been harvested for taffy apples. This variety is averaging 5 for the starch test, over the starch threshold of 3.5, considered mature. The current average firmness reading of 16.3 pounds is close to the long-term controlled atmosphere target value of 16 pounds. The predicted peak harvest date for Central Berrien County is Sept. 14.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sept. 5 |
65 (30-98) |
16.3 (15.4-17.1) |
5 (4.6-5.6) |
10.1 (9.4-11.6) |
*Starch values according to the 1-8 scale developed by Cornell University.
Apple maturity sampling parameters
- Color % = the visual percentage of red color (blush) from 0 to 100; range is of all fruits tested.
- Firmness in pounds pressure = measured with a FT Penetrometer; 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.
- Starch for Honeycrisp: a separate starch chart for Honeycrisp apples developed by Washington State University (scale 1-6).
- 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.
|
Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety. |
|||||
|
Variety |
Firmness (pounds)* |
Starch Index* |
|||
|
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 |
7 |
|
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 |
See the following helpful resources for more information:
- Predicted apple harvest dates for 2023 from MSU Extension.
- More information on harvest management tools and timings from MSU Extension.
- Post harvest treatments to extend apple life.
- Guidelines from MSU Extension 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.
