Southwest Michigan apple maturity report – October 2, 2024
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EmailApple harvesting in southwest Michigan is rounding the last turn and will be wrapping up soon.
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
Commercial apple harvesting is wrapping up in southwest Michigan with less than one-third of the Fuji, Braeburn and Evercrisp orchards remaining to be picked. Relatively warm conditions in 2024 pushed ripening earlier than normal.
Internal watercore continues to increase in late harvested Evercrisp. Watercore does not increase in fruit once harvested and may disappear in storage if not severe. Apples severely affected may develop browning and unpleasant fermentation flavors. The solution is to avoid late harvesting of watercore-prone varieties in years such as 2024 when the disorder is prevalent.
Fuji (main season)
This variety is averaging 4.6 for the starch test—it reached the mature starch threshold of 3 for fresh market approximately two weeks ago. The average firmness remains close to 18 lbs, the desired minimum firmness for long-term controlled atmosphere (CA) storage. Picking is approximately two-thirds done in Berrien County area Fuji orchards. Unlike Evercrisp, watercore does not seem to be a significant problem in Fuji in southwest Michigan this year based on the samples we tested.
|
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) |
|
Sep. 16 |
60.4 (40-82) |
18.8 (17.3-21.6) |
3 (2.2-3.8) |
12.1 (11.3-14.1) |
|
Sep. 23 |
74.7 (55-91.5) |
17.7 (16.6-20) |
3.9 (3.2-4.8) |
12.8 (11.6-15.3) |
|
Sep. 30 |
63 (45-88) |
18.4 (16.7-19.5) |
4.6 (4-5.4) |
13.9 (11.1-16.5) |
*Starch values according to the 1-8 scale developed by Cornell University.
Rome
This variety is averaging 4.3 for the starch test, like the previous week, and exceeding the mature starch threshold of 3. The current average firmness reading is 19.2 lbs, slightly less than last week. The desired minimum firmness for long-term CA storage is 18 lbs. The area Romes matured slightly ahead of the predicted peak harvest date for Central Berrien County of Sept. 24. Most of the area Rome have already been picked for processing.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 16 |
69.6 (50-89) |
20.5 (19.9-21.4) |
3 (3-3) |
12.1 (10.2-11.8) |
|
Sep. 23 |
80.1 (75-89) |
20.1 (18.5-21.7) |
4.2 (3.2-4.8) |
11.2 (9.4-12.1) |
|
Sep. 30 |
87.6 (70-91) |
19.2 (17.4-22) |
4.3 (3-5.8) |
10.8 (9.2-11.9) |
*Starch values according to the 1-8 scale developed by Cornell University.
Evercrisp
This variety is averaging 3.2 for the starch test. The optimal starch value for long-term CA storage is 2.5, the mature target threshold for more immediate consumption is 3. The current average firmness reading is 22.3 lbs, about the same as last week. The desired firmness for long-term CA storage is 22 lbs. More fruit are showing internal watercore this week. Picking can be delayed waiting for better size, blush and brix, but increases the chances for watercore in the orchard, and subsequent internal browning in storage. Approximately two-thirds of the Berrien County area Evercrisp orchards have been harvested.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 16 |
66 (57.5-75) |
23.9 (22.3-25.5) |
1.9 (1-3) |
13.2 (12.5-14.7) |
|
Sep. 23 |
59 (50-62.5) |
22.6 (20.9-24.5) |
2.2 (1.8-3.2) |
13.5 (12.1-14.7) |
|
Sep. 30 |
73 (65-82) |
22.3 (19.3-23.7) |
3.2 (2.4-4.4) |
15.2 (12.8-17.4) |
*Starch values according to the 1-8 scale developed by Cornell University.
Braeburn
This variety was sampled for the second week. The starch conversion index is averaging 4. The minimum recommended starch value for lon-gterm CA storage is 2.5, so this variety is maturing ahead of the predicted harvest date for central Berrien County of Oct. 9. The current average firmness reading is 20.3 lbs, the desired firmness for long-term CA storage is 18 lbs. Picking has started in Berrien County Braeburn orchards.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|---|---|---|---|---|
|
Sep. 23 |
60.8 (35-77) |
22.7 (20.3-21.5) |
3.4 (2.6-4.6) |
12.4 (9.6-16.1) |
|
Sep. 30 |
47.5 (35-60) |
20.3 (19.1-21.6) |
4 (3-5) |
11.1 (10.2-12) |
*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.
