Southwest Michigan apple maturity report – September 4, 2024
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EmailVery warm weather over the past week and earlier in the season has been pushing along fruit ripening.
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.
Overview for this week
Harvesting of Gala and Jonathan fruit in the southwest Michigan region is generally done. Picking is now focused on Honeycrisp. Fruit continues to ripen quickly in southwest Michigan due to heat spike in late June and early September this year.
Gala (Standard)
The table gives a summary for main season Gala varieties sampled from three orchards in Berrien County. Most Gala in the area have been harvested. The current average firmness of 12.5 dropped significantly from last week’s 17.2 lbs. and is too soft for successful storage in controlled atmosphere (CA) storage rooms. The predicted harvest date for 2024 for central Berrien County is Aug. 24, which is approximately two weeks ahead of the normal date of Sept. 8 for the region.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|
|
Aug. 19 |
86 (70-98) |
18.9 (16-22) |
5.0 (2.8-7.4) |
11.6 (11-12.3) |
|
Aug. 26 |
87 (70-97) |
17.2 (14.7-22.3) |
6.0 (4.2-7.0) |
12.8 (12.1-13.4) |
|
Sep. 3 |
99 (97-100) |
12.5 (12-13) |
7.6 (7.2-8) |
12.9 (12.3-14.1) |
*Starch values according to the 1-8 scale developed by Cornell University.
Honeycrisp
Starch conversion for this variety jumped from 5 for last week to 6.8 this week, well into the mature range. The mature starch threshold is 3.5. Fruit are internally mature. It is best to harvest prior to 6 on the starch scale for best storage characteristics. The current average firmness reading is 13.7 lbs., below the recommended firmness for short-term CA storage (15 lbs.). This variety is maturing ahead of the predicted peak harvest date for central Berrien County of Aug. 29. Refer to this article by MSU researcher Randy Beaudry on Honeycrisp harvest and storage recommendations. As of early this week, many Honeycrisp orchards remained to be harvested.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Aug. 19 |
48.0 (45-55) |
15.7 (14.3-16.4) |
1.9 (1.4-2.8) |
10.8 (10.3-11.4) |
|
Aug. 26 |
56.6 (35-67.5) |
14.9 (14.2-15.6) |
5 (4.2-6.0) |
11.6 (11.1-12.1) |
|
Sep. 3 |
60 (55-72.5) |
13.7 (12.7-15) |
6.8 (5-7.4) |
13 (12.6-13.5) |
*Starch values according to the 1-8 scale developed by Cornell University.
Empire
This variety is averaging 3.5 for the starch test—the mature starch threshold is 3.5. The current average firmness reading is 17.3 lbs., compared to the desired minimum firmness for long-term CA storage of 16 lbs. The predicted peak harvest date for central Berrien County for fresh market CA storage is Sept. 7, which is on target. Approximately half of the area Empire have been harvested, mainly for taffy apples.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Aug. 26 |
59.3 (40-89) |
18.3 (17.4-19.7) |
2.2 (1.6-3.0) |
11.0 (9.9-12.3) |
|
Sep. 3 |
75 (55-97.5) |
17.3 (16.6-17.6) |
3.5 (2.6-4.2) |
11.3 (20.8-12.4) |
*Starch values according to the 1-8 scale developed by Cornell University.
Golden Delicious
This variety is averaging 2.6 for the starch test—the mature starch threshold for fresh market is 3. The current average firmness reading is 16.7 lbs., the desired minimum firmness for long-term CA storage is 17 lbs. This variety is ripening ahead of the predicted peak harvest date of Sept. 13 for central Berrien County. Exposed surfaces of this variety show strong red blush in some orchards due to heat and sunlight. Very few goldens have been harvested so far in central Berrien County.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 3 |
35.9 (20-30) |
16.7 (15.8-18.2) |
2.6 (1.6-3.2) |
11.5 (10.7-12.3) |
*Starch values according to the 1-8 scale developed by Cornell University.
Jonagold
This variety is averaging 2.6 for the starch test—the mature starch threshold for fresh market is 3.5. The current average firmness reading is 19.4 lbs., the desired minimum firmness for long-term CA storage is 17 lbs. The predicted peak harvest date for central Berrien County is Sept. 10. Most Jonagold orchards have not been harvested yet in Berrien County.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 3 |
62.6 (37.5-89) |
19.4 (16.4-22) |
2.6 (2-4) |
12.3 (11.4-13.4) |
*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 shown is for the orchard averages.
- Firmness in lbs pressure, skin off, as measured with a FT Penetrometer; range is for the site averages.
- Starch: 1 = all starch (solid blue staining), 8 = no starch (white); range is for the site averages. Starch Iodine Index Chart.
- Brix = % sugar measured with Atago PAL-1 Pocket Refractometer
|
Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety. |
|||||
|---|---|---|---|---|---|
|
Variety |
Firmness (lbs)* |
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 |
|
Braeburn |
16 |
17 |
18 |
2.5 |
7 |
See the following helpful resources for more information:
- Predicted apple harvest dates for 2024 from MSU Extension.
- The 2024 Michigan apple crop forecast, as given at the USApple Outlook meeting
- 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.
