West central Michigan apple maturity report – October 19, 2022
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EmailRain and cool weather moved in across the region this week. Idared are being harvested at many orchards. EverCrisp and Aztec Fuji may be ready to harvest depending on storage requirements.
Apple maturity testing will occur weekly for the west central region beginning now through the end of apple harvest. Reports will be sent out every week, following the Wednesday morning the Michigan State University Extension fruit team apple maturity calls.
In the west central region, growers are working to finish harvesting many varieties. Idared and Aztec Fuji are showing signs of maturity. Evercrisp and Pink Lady are closer to maturity. Apple harvest is moving steadily, and fruit continue to size more than expected. Red color development has been excellent, and sugar levels continue to increase.
Weather over the past week has been very cool and wet. Heavy rainfall and windy conditions occurred across the region. For the rest of the week, temperatures should increase each day. This weekend, highs will be in the 60s degrees Fahrenheit with lows in the 50s F. As of Oct. 18, the Enviroweather station for Hart has reported little accumulation of degree days since last week with 3782 DD42 and 2441 DD50.
As fruit harvest continues, growers should consider applying preharvest fungicides to minimize storage rots. As a reminder, with regular rain events, growers should maintain fungicide coverage to minimize late season rots, particularly for fruit that will be in long-term storage. Rainfall over 2 inches can wash off fungicide residues on fruit. Excessive rain may also have an impact on fruit by temporarily diluting flavor and brix (sugars).
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 three locations across Oceana County.
For more information about apple maturity testing, review these resources compiled by Anna Wallis and Amy Irish Brown, MSU Extension.
- Predicted apple harvest dates for 2022 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.
- 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
Aztec Fuji
Fruit were sampled from two locations on Oct. 17 in Oceana County. Background color is transitioning from light green to more yellow. Red color development improved slightly to 82% on average, but this varied by location. Fruit firmness decreased this week to an average of 14.1. Starch clearing is 5.5, and sugars levels are excellent at 14 according to the Brix table below. Some watercore was present at all locations sampled.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Oct 10 |
219 (245-189) |
80.8 (98-60) |
2.7 (4-1) |
16.3 (20.6-13.1) |
3.8 (6-2) |
13.6 (13.9-13.4) |
|
Oct 17 |
234 (248-220) |
82 (95-65) |
2.75 (3-2) |
14.1 (16.9-11.1) |
5.5 (7-4) |
14 (14-14) |
Evercrisp
Fruit were sampled from three locations on Oct. 17 in Oceana County. Red color still needs some time to develop, and background color is still quite green. Fruit are generally very firm with an average of 20.4. Starch clearing has advanced to an average rating of 4.2 this week. Penn State University recommends using a starch index of 4-6 for long-term storage and 6-7 for direct sales markets. Sugar levels are excellent for this variety. Similar to its Fuji parentage, watercore was present at all locations samples.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Oct 10 |
261 (269-255) |
68.8 (95-50) |
3. 7 (5-2) |
21.5 (27.4-16.6) |
3.1 (6-2) |
15.8 (18.3-14.4) |
|
Oct 17 |
277.8 (289-263) |
65 (90-45) |
3.5 (5-2) |
20.4 (24.5-15.9) |
4.2 (7-2) |
16.1 (17.9-14.1) |
Pink lady
Fruit were sampled from one location on Oct. 17 in Oceana County. Fruit were smaller in size than other varieties, but it improved from last week. A vibrant pink blush was present on fruit. Background color is pale green to yellow at an average of 2.6 at this location. Fruit were very firm with an average pressure of 19.1 lbs. On average, starch clearing is 2.1, and sugars levels are excellent. This variety is still slightly immature.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Oct 10 |
170 (175-165) |
61 (75-45) |
3.2 (4-2) |
18.8 (23.7-15.1) |
2.4 (6-1) |
14.1 (14.9-13.3) |
|
Oct 17 |
196 |
64 (80-45) |
2.6 (3-2) |
19.1 (21.8-17.4) |
2.1 (3-2) |
15 |
Apple maturity sampling parameters
- Ethylene (% fruits with internal ethylene over 0.2 ppm) = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
- 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: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
- Starch For Honeycrisp: will typically be rated using the standard Cornell SPI 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 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 |
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 |
|
Brix Guide |
Low |
Fair |
Good |
Excellent |
|
All varieties |
Less than 11 |
11 |
12 |
13 |
|
Honeycrisp |
Less than 12 |
12 |
12 |
Greater than 14 |
