West central apple maturity report – September 21, 2022
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EmailGala and Honeycrisp are being harvested this week in the West central region. Jonagold and Empire are moving closer to maturity.
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 Michigan State University Extension fruit team apple maturity calls.
In the West Central region, growers are harvesting Gala and Honeycrisp this week. Some growers have also harvested September Wonder Fuji. Jonagold and Empire are showing signs of maturing this week. Golden Delicious and Red Delicious are still immature. Overall, apple harvest is moving steadily, crop load is excellent, and red color continues to develop well.
Weather over the past week has generally been warm with rain showers. Daytime temperatures have ranged from the low 70s Fahrenheit to low 80s F, and nighttime temperatures have been in the 50s F and 60s F. As of Sept. 20, the Enviroweather station for Hart, MI has reported an accumulation of 3546 DD42 and 2341 DD50.
Storms brought rain across the region on Tuesday, Sept. 20 during the day and overnight. The Hart Enviroweather station reported rainfall of 0.37 inches on Tuesday this week. Rain is also forecasted for Thursday, Sept. 22, along with cooler nighttime temperatures that will be dipping down into the 40s F. High temperatures are forecasted to be in the upper 50s F and low 60s F. Cooler temperatures and early leaf color change in forest trees are sure signs of fall as we enter into autumn with the Autumn Equinox on Thursday, Sept. 22!
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 two 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 three to five 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.
Empire
Fruit were sampled from three locations on Sept. 19 in Oceana County. Red color development is good with an average of 69.5%. Background color is still quite green but is improving. Average fruit firmness is at 16.4 but varied across locations. Starch clearing is still light. Sugar levels are improving and are considered fair according to the Brix table below. This variety still needs a little more time before it is mature for long-term storage.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 12 - 13 |
149 (163-138) |
68.7 (90-45) |
4.0 (5-3) |
16.2 (19.2-13.6) |
2.6 (4-1) |
10.4 (11-9.7) |
|
Sept 19 |
166 |
69.5 |
4.2 (5-3) |
16.4 |
2.1 (4-1) |
11.2 |
Jonagold
Fruit were sampled from three locations on Sept. 19 in Oceana County. Red color development is good, and background color is light green. Fruit firmness varied from site to site with an average of 15.3. Pressure was still good in tested fruit. Recommended pressure for this variety is 15-17, depending on the intended storage time. On average, more starch is being converted to sugar, and the starch rating is 3.8. Sugars levels are good at 12.8 according to the Brix table below. Some fruit at one location also had mild water core.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 12 |
203 (238-183) |
72.6 (98-30) |
3.6 (4-3) |
16.0 (19-12.9) |
2.2 (4-1) |
12.1 (12.6-11.6) |
|
Sept 19 |
223 (240-204) |
74.1 (95-45) |
3.3 (5-2) |
15.3 |
3.8 (8-1) |
12.8 (13.5-12.3) |
Golden Delicious
Fruit were sampled from three locations on Sept. 19 in Oceana County. This variety is still immature, but it is showing early signs of maturity. Background color is generally light green with fruit beginning to show more yellow. Some fruit are also showing a light blush with a touch of pink. Fruit firmness varied from site to site with an average of 16.1. On average, starch clearing is low at 2.3, and sugars levels are good at 12.9 according to the Brix table below.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 19 |
191 (192-190) |
16.3 (45-0) |
3.1 (4-2) |
16.1 (19.5-13.6) |
2.3 (4-1) |
12.9 (13.9-11.7) |
Red Delicious
Fruit were sampled from two locations on Sept. 19 in Oceana County. Red color development is very good with most fruit being fully red. Fruit firmness varied from site to site with an average of 15.8. On average, starch clearing is low, and sugars levels are still low according to the Brix table below. This variety is still immature.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 19 |
204 (217-192) |
91.4 (100-65) |
5 (5-5) |
15.8 (18.0-13.9) |
1.6 (2-1) |
10.3 (10.5-10.0) |
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 |