Southwest Michigan apple maturity report – October 3, 2023
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EmailSouthwest Michigan apple harvest focuses on Fuji, Yellow Delicious and Red Delicious apples.
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
Later season varieties Red Delicious, Fuji, Braeburn and Evercrisp (a Honeycrisp by Fuji cross) have susceptibility to watercore. Watercore is worse in years when late harvesting and weather conditions advances fruit maturity, especially internal starch conversion. Weather conditions hastening internal starch conversion include cool nights (below 40 degrees Fahrenheit) and sunny days.
Fuji
Main season Fuji varieties are averaging 4.5 for the starch test, significantly above the starch threshold of 3, considered mature. The current area average firmness reading is 17.4 pounds, compared to the long term controlled atmosphere (CA) target value of 18 pounds, and the same as the last two weeks. This variety appears to have matured slightly ahead of the predicted peak harvest date of Sept. 23 for central Berrien County. Brix has improved slightly since last week. A few main season Fujis have been harvested but most are still on the tree.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 12 |
65.8 (40-98) |
19.2 (17.9-20) |
2.5 (2-3) |
10.8 (10.1-12) |
|
Sep. 19 |
63.1 (30-90) |
17.4 (15-18) |
3.3 (2.6-4.6) |
10.7 (9.9-11.1) |
|
Sep. 25 |
67 (30-90) |
17.4 (16.9-18.2) |
4.2 (3.6-5.2) |
11.7 (11-12.2) |
|
Oct. 2 |
67.9 (60-75) |
17.4 (16.9-17.9) |
4.5 (3.8-6) |
12.1 (11.8-12.8) |
*Starch values according to the 1-8 scale developed by Cornell University.
Golden Delicious
This variety is averaging 6.4 for the starch test, a jump since last week and considerably above the starch threshold of 3 consider mature. The current average firmness reading of 15.4 pounds is about 1 pound lower this week, and considerably below the long term CA target value of 17 pounds. The predicted peak harvest date for central Berrien County is Sept. 24. Background color is light green to yellow. Goldens have been harvested in approximately 50% of the central Berrien County area.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 12 |
16.6 (8-40) |
16.9 (16-17.3) |
2.3 (1-3.6) |
11.2 (9.9-11.9) |
|
Sep. 19 |
14.8 (0-45) |
16.5 (15.4-17.8) |
3.7 (2-6) |
11.8 (10.7-13.3) |
|
Sep. 25 |
20.3 (5-50) |
16.8 (15.2-17.9) |
4.8 (2-6.6) |
12.4 (11.4-13.6) |
|
Oct. 2 |
29 (5-20) |
15.4 (14.1-17.1) |
6.4 (5.2-7.8) |
12.7 (12-13.2) |
*Starch values according to the 1-8 scale developed by Cornell University.
Red Delicious
This variety is averaging 5.5 for the starch test, the mature starch threshold is 2.5. The current average firmness reading is 16.3 pounds compared to the long term CA target value of 18 pounds. The predicted peak harvest date for central Berrien County is Sept. 27. Harvesting of this variety has begun in earnest in the central Berrien County area.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 19 |
97.2 (85-99) |
17 (15.9-17.5) |
3 (2.4-3.6) |
10.4 (9.6-11.6) |
|
Sep. 25 |
96.8 (70-100) |
16.6 (15.6-17.7) |
4.1 (3.6-4.6) |
10.7 (9.4-12.7) |
|
Oct. 2 |
100 (100) |
16.3 (15.3-18.3) |
5.5 (4.8-7) |
12.7 (11.6-14.3) |
*Starch values according to the 1-8 scale developed by Cornell University.
IdaRed
This variety is averaging 3.7 for the starch test, the mature starch threshold is 3.5. The current average firmness reading is 15.4 pounds, compared to the long term CA target value of 16 pounds. The predicted peak harvest date for central Berrien County is Oct. 4, and appears to be generally correct. A few IdaRed orchards have been harvested in the area.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 19 |
74.6 (50-98) |
16.5 (16-17) |
2.5 (2-3) |
11 (10.4-11.5) |
|
Sep. 25 |
82.6 (50-98) |
16.9 (15.6-17.8) |
3.2 (3-3.8) |
11.4 (10.6-11.8) |
|
Oct. 2 |
84.9 (60-100) |
15.6 (15.4-16.2) |
3.7 (3.2-4.2) |
11.5 (10-12.1) |
*Starch values according to the 1-8 scale developed by Cornell University.
Rome
This variety is averaging 4 for the starch test, the mature starch threshold is 3. The current average firmness reading of 19.9 pounds is still firm—the long term CA storage target value for this variety is 18 pounds. The predicted peak harvest date for central Berrien County is Oct 4.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 19 |
84.2 (60-100) |
21.8 (20.1-25) |
3.2 (2.4-3.8) |
10.4 (9.9-10.7) |
|
Sep. 25 |
82.5 (50-98) |
22.5 (19.9-24.6) |
3.6 (3-4.4) |
10.7 (10-11.4) |
|
Oct. 2 |
88.1 (70-100) |
19.9 (19-22) |
4 (3.4-4.6) |
10.9 (10.4-11.5) |
*Starch values according to the 1-8 scale developed by Cornell University.
Evercrisp
This variety is averaging 3.3 for the starch test, the mature starch threshold is 3. The current average firmness reading of 21.2 pounds is very firm—the long term CA storage target value for this variety is 18 pounds. We currently do not have a predicted harvest date for this variety, but based on the firmness and starch tests, it is at least two weeks off. Brix has reached 13 and fruit are starting to eat well.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 25 |
67.5 (50-90) |
23.4 (22.7-25.4) |
1.7 (1-3) |
12.6 (10.9-13.3) |
|
Oct. 2 |
70 (50-90) |
21.2 (19.6-22.4) |
3.3 (2.4-3.6) |
13 (12.3-14.4) |
*Starch values according to the 1-8 scale developed by Cornell University.
Braeburn
This variety is averaging 3.7 for the starch test, the mature starch threshold is 2.5. The current average firmness reading of 20.3 pounds is very firm—the long term CA storage target value for this variety is 18 pounds. Brix is still relatively low.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Oct. 2 |
68.5 (50-98) |
20.3 (18.7-22.2) |
3.7 (2.6-4.6) |
10.9 (9.7-11.4) |
*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 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.
