Southwest Michigan apple maturity report – September 11, 2024
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EmailApple harvesting in southwest Michigan is moving rapidly.
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
Picking has focused on harvesting of Jonagold and Honeycrisp over the past week in central Berrien County. More moderate temperatures over the past week slowed apple maturation.
Honeycrisp
Internal starch conversion for this variety for the last three weeks averaged 5, 6.8 and now 7.3, very mature. The mature starch threshold is 3.5. Fruit are internally mature. The current average firmness reading is 13.5, below the recommended firmness for short-term controlled atmosphere (CA) storage (15 lbs). The predicted peak harvest date for central Berrien County is Aug. 29. Refer to this article by MSU researcher Randy Beaudry on Honeycrisp harvest and storage recommendations. As of early this week, about half of the area Honeycrisp orchards remained to be harvested or finished harvesting.
|
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) |
|
Sep. 10 |
70 (60-75) |
13.5 (12.3-14.4) |
7.3 (7-7.6) |
13 (11.3-15) |
*Starch values according to the 1-8 scale developed by Cornell University.
Empire
This variety is averaging 4 for the starch test—the mature starch threshold is 3.5. The current average firmness reading is 17.3 lbs, about the same as last week, still close 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 still is on target. Approximately half of the area Empire remain to be harvested.
|
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) |
|
Sep. 9 |
87 (72-97) |
17.3 (15-17.9) |
4 (2.8-4.8) |
11.4 (10.8-12.6) |
*Starch values according to the 1-8 scale developed by Cornell University.
Golden Delicious
This variety is averaging 3.1 for the starch test, considered mature—the mature starch threshold for fresh market is 3. The current average firmness reading is 16.7 lbs, about the same as last week, the desired minimum firmness for long-term CA storage is 17 lbs. This variety is ripening close to the predicted peak harvest date of Sept. 13 for central Berrien County. Picking has not started in most Golden Delicious orchards 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) |
|
Sep. 9 |
30 (20-40) |
16.7 (15.4-18.4) |
3.1 (2.2-3.6) |
12.2 (11.7-12.5) |
*Starch values according to the 1-8 scale developed by Cornell University.
Jonagold
This variety is averaging 4.9 for the starch test, a jump from last week’s 2.6 reading—the mature starch threshold for fresh market is 3.5. The current average firmness reading is 17.3 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 area Jonagold orchards have been picked or are in the process of being picked.
|
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) |
|
Sep. 9 |
74 (50-96) |
17.3 (16.2-20) |
4.9 (3.4-6.6) |
13 (12.1-15.6) |
*Starch values according to the 1-8 scale developed by Cornell University.
Red Delicious
This variety was sampled for the first time this week. This variety is averaging 2.8 for the starch test—the mature starch threshold for fresh market is 2.5. The current average firmness reading is 17.9 lbs—the desired minimum firmness for long-term CA storage is 18 lbs. This variety is maturing slightly ahead of the predicted peak harvest date of Sept. 17 for Red Delicious in central Berrien County. Picking has not started in most Red Delicious orchards in central Berrien County.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 9 |
99 (96-100) |
17.9 (17.3-19) |
2.8 (2-3.2) |
10.3 (9.7-11.1) |
*Starch values according to the 1-8 scale developed by Cornell University.
Fuji (main season)
This variety is averaging 2.8 for the starch test—the mature starch threshold for fresh market is 3. The current average firmness reading is 19.1 lbs, the desired minimum firmness for long-term CA storage is 18 lbs. The predicted peak harvest date for central Berrien County is Sept. 13, which seems to be on target. Picking can be delayed waiting for better size, blush and brix. Picking has not started in Berrien County area Fuji orchards.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 9 |
51 (40-72) |
19.1 (17.7-21.5) |
2.8 (2-3) |
11.5 (9.9-13.2) |
*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.