West central Michigan apple maturity report – September 18, 2024
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EmailJonagold are being harvested in the west central region. High daytime temperatures mean apples are continuing to mature ahead of schedule.
In the west central region, harvest of September Wonder Fuji, Jonagold and Empire is wrapping up. Mutsu, Idared (Figure 1) and Golden Delicious were tested for maturity this week. Dry and sunny days have allowed growers to continue harvesting through varieties as they mature. Some Mutsu had water core this week.
Weather over the past week has been unusually hot with above normal temperatures in the 80s and weekend temperatures close to 90 degrees Fahrenheit. High temperatures will remain in the 80s over the next few days and will cool down into the 70s this weekend and into next week. There is little rain in the forecast so conditions will be hot and dry over the next few days with some possibility of rain forecasted for Sunday. Using harvest management tools is recommended for varieties that will be mature soon.
How to read maturity tables
Each week, an apple maturity report will be provided and will include average values for several apple samples for varieties nearing maturity. Maximum and minimum values are included in tables below for the highest and lowest individual fruits evaluated for each to give a full spectrum of maturity. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted. Samples were collected from two to five locations across Oceana County (Figures 2-3).
For more information about apple maturity testing, review these resources compiled by the Michigan State University Extension tree fruit team.
- Predicted apple harvest dates for 2024 from MSU.
- More information on harvest management tools and timings can be found in this article.
- Guidelines from MSU to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety.
- New starch charts for evaluating apple maturity in Michigan from Michigan State University
- Predicting apple maturity and starch chart from Cornell University.
- Starch chart for Honeycrisp Apples developed by Washington State University.
Maturity information for the west central region
Rome
Fruit were sampled at two locations in Oceana County this week. Fruit will mature soon at some locations. Rome is considered mature at a starch rating of 3. Fruit are dark red with percent coverage at 95%, similar to last week. Fruit firmness decreased slightly, and fruit is still very firm at 21.8 pounds (lbs) pressure. Starch is 2.4, and sugars are similar to last week at 10.4 degrees Brix.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 9 |
173 (188-159) |
96 (100-60) |
3.1 (4-1) |
25.5 (29.4-21.6) |
1.8 (3-1) |
10.5 (11.0-9.9) |
|
Sept 16 |
192 (194-189) |
95 (100-60) |
3.3 (4-1) |
21.8 (26.3-19.1) |
2.4 (3-1) |
10.4 (11.0-9.8) |
Mutsu/Crispin
Fruit were sampled at two locations in Oceana County this week. Fruit are still immature. There is some blush although fruit are still green. Background color is light green, and firmness is similar to last week at 18.8 lbs pressure. Starch is 2.2, and sugars are 12.3 Brix.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 9 |
301 (343-259) |
25 (45-2) |
4.8 (5-4) |
18.6 (21.5-16.1) |
1.9 (3-1) |
11.3 (11.5-11.1) |
|
Sept 16 |
328 (346-311) |
31 (50-0) |
4.7 (5-4) |
18.8 (21.1-17.0) |
2.2 (7-1) |
12.3 (12.9-11.7) |
Golden Delicious
Fruit were sampled at five locations in Oceana County this week. Fruit are mature at some locations and are light green. Some blush was observed this week. Firmness is 16.9 lbs pressure, and recommended pressure for long-term storage is 17. Starch is 2.9, and fruit are considered mature at a starch rating of 3. Sugars have increased and are excellent at 13 Brix according to the table below.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 9 |
170 (190-142) |
27 (60-0) |
4.0 (5-2) |
18.0 (21.0-15.1) |
1.7 (4-1) |
12.5 (12.6-12.3) |
|
Sept 16 |
190 (250-158) |
28 (50-0) |
3.7 (5-2) |
16.9 (22-12.8) |
2.9 (5-1) |
13.0 (13.9-12.0) |
Red Delicious
Fruit were sampled at three locations in Oceana County this week. Fruit are still immature, and red color development is at 98%. Background color is yellow green, and firmness is 17.7 lbs pressure. Pressure recommended for long-term storage is 18 lbs. Starch is 1.7, and sugars are 10.3 Brix. Red delicious are considered mature with a starch rating of 2.5.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 9 |
151 (180-122) |
98 (100-95) |
1.4 (3-1) |
18.2 (21.9-16.0) |
1.4 (2-1) |
10.0 (10.3-9.7) |
|
Sept 16 |
165 (179-156) |
97 (100-70) |
2.2 (4-1) |
17.7 (20.5-16.2) |
1.7 (5-1) |
10.3 (11.2-9.7) |
Idared
Fruit were sampled at three locations in Oceana County this week. Fruit are immature. Red color development is at 75%. Background color is light green, and firmness is 18.4 lbs pressure. Pressure recommended for long-term storage is 16 lbs, and fruit are considered mature with a starch rating of 3.5. Starch is 1.9, and sugars are 11.4 Brix.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 16 |
197 (260-167) |
75 (99-50) |
3.7 (4-3) |
18.4 (21.6-14.3) |
1.9 (3-1) |
11.4 (12.4-10.6) |
Ambrosia
Fruit were sampled at two locations in Oceana County this week. Fruit are immature. Red color development is at 56%, and fruit have a beautiful pink blush. Background color is light green, and firmness is 18.2 lbs pressure. Starch is 2.2, and sugars are 11.6 Brix. Fruit can mature quickly so it may be important to test Ambrosia blocks every few days as fruit get more mature to pick at the correct timing for optimal flavor and storage.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|---|---|---|---|---|---|---|
|
Sept 16 |
220 (255-186) |
56 (70-40) |
3.2 (4-3) |
18.2 (23.3-15.1) |
2.2 (5-1) |
11.6 (12.4-10.7) |
Apple maturity sampling parameters
- Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested. Indicates surface area covered in red and intensity of red color.
- Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
- Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
- Starch for Honeycrisp: will typically be rated using the standard Michigan State University starch scale (1-8). However, a separate starch chart for Honeycrisp apples developed by Washington State University (scale 1-6) also exists.
- Brix = % sugar measured with Atago PAL-1 Pocket Refractometer
Looking for more? View Michigan State University Extension’s Apple 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 |
6 |
|
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 |
|
Brix Guide |
Low |
Fair |
Good |
Excellent |
|---|---|---|---|---|
|
All varieties |
Less than 11 |
11 |
12 |
13 |
|
Honeycrisp |
Less than 12 |
12 |
12 |
Greater than 14 |