Southwest Michigan apple maturity report – September 25, 2024
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EmailApple harvesting in southwest Michigan is focused on late season varieties.
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 of IdaRed and Golden Delicious is nearly done in central Berrien County. Maturation of Romes and Braeburn is moving rapidly. The harvest season will be wrapping up early this year. Summer rots of fruit have been more prevalent this year due to heat and sunlight stress on fruit, weakening the protective waxy surface of the apple.
Commonly grown cultivars such as Red Delicious, Fuji, Honeycrisp, Jonagold, Granny Smith and Braeburn can have problems with watercore. Even some of our newer cultivars like Evercrisp (a Honeycrisp by Fuji cross) have susceptibility to watercore. Advanced maturity (ripe fruit) is a required feature for the development of watercore, so factors such as hot days, and hot days plus cool nights, that advance fruit maturity can promote watercore development.
Red Delicious
This variety was sampled for the third week. This variety is averaging 4.4 for the starch test, well into the mature range—-the mature starch threshold for fresh market is 2.5. The current average firmness reading is 17.1 lbs—the desired minimum firmness for mid-term controlled atmosphere (CA) storage is 17 lbs. This variety matured slightly ahead of the predicted peak harvest date of Sept. 17 for Red Delicious in central Berrien County. Picking has finished in about half of the 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) |
|
Sep. 16 |
98.3 (95-100) |
17.3 (16-18) |
3.3 (2.8-4.2) |
11.3 (10.4-12.5) |
|
Sep. 23 |
98.2 (94-100) |
17.1 (16-17.9) |
4.4 (3.4-5) |
13.0 (11.6-14.0) |
*Starch values according to the 1-8 scale developed by Cornell University.
Fuji (main season)
This variety is averaging 3.9 for the starch test—this variety reached the mature starch threshold for fresh market of 3 last week. The current average firmness reading is 17.7 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 is approximately 2/3 done 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) |
|
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) |
*Starch values according to the 1-8 scale developed by Cornell University.
IdaRed
This variety is averaging 3.9 for the starch test, considered mature because it is above the mature starch threshold of 3.5. The current average firmness reading is 14.7 lbs, close to the minimum firmness of 15 lbs suitable for mid-term CA storage. This variety matured slightly ahead of the predicted peak harvest date of Sept. 24 for Central Berrien County. Picking of IdaRed is nearly finished in Berrien County area orchards.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sep. 16 |
71.1 (60-77.5) |
16.3 (15.1-18.4) |
2.7 (2-3.8) |
11.6 (10.7-12.5) |
|
Sep. 23 |
74.7 (55-91.5) |
14.7 (12.2-16.5) |
3.9 (3-5.2) |
12.3 (11.5-13.4) |
*Starch values according to the 1-8 scale developed by Cornell University.
Rome
This variety is averaging 4.2 for the starch test—exceeding the mature starch threshold of 3. The current average firmness reading is 20.1 lbs, about the same as 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. Picking can be delayed if desired to wait for better size, and brix, but will increase the risk for color bleeding into the flesh from the peel. Approximately 2/3 of the area Romes have been picked.
|
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) |
*Starch values according to the 1-8 scale developed by Cornell University.
Evercrisp
This variety is averaging 2.2 for the starch test—the optimal starch value for longterm CA storage is 2.5, the mature threshold is 3. The current average firmness reading is 22.6 lbs, the desired firmness for long-term CA storage is 22 lbs. Picking can be delayed waiting for better size, blush, and brix, but increases the chances for internal disorders in storage. Picking has not started in Berrien County area Evercrisp orchards. A few more fruit are showing internal water core this week.
|
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) |
*Starch values according to the 1-8 scale developed by Cornell University.
Braeburn
This variety was sampled for the first time this week. The starch conversion index is averaging 3.4—the minimum recommended starch value for longterm CA storage is 2.5. The current average firmness reading is 22.7 lbs, the desired firmness for long-term CA storage is 18 lbs. Picking can be delayed waiting for better size, blush, and brix. Picking has not started in Berrien County Braeburn orchards. The predicted harvest date for central Berrien County is Oct. 9th.
|
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) |
*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.
