West central Michigan apple maturity report – October 11, 2023
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EmailCool weather is here to stay. Golden Delicious, Red Delicious and Mutsu are being harvested this week. The later varieties, EverCrisp and Pink Lady, are starting to mature.
Apple maturity testing will occur weekly for the west central Michigan region beginning now through the end of harvest. Reports will be sent out every week following the Michigan State University Extension fruit team apple maturity calls on Wednesday mornings.
In the west central region, growers are harvesting Golden Delicious, Red Delicious and Mutsu. Some growers will be harvesting Idared soon with Aztec Fuji to follow. EverCrisp and Pink Lady are also mature and could be harvested for long-term harvest. Fruit for those varieties are still very firm. Some growers are applying ReTain or Harvista to manage harvest crews. Crop loads are high this season, and crews are working diligently to harvest and work through varieties.
Weather update
The weather over the past week has been cool and rainy. Temperatures dipped down into the 30s across the region on Oct. 8 and 9. Sugar levels continue to be good or excellent across varieties. There is a high level of variability in fruit maturity within trees and across blocks this season. Testing fruit maturity for individual blocks is important this year to identify best harvest timing.
As of Oct. 10, the Michigan State University Enviroweather station for Hart has reported an accumulation of 3,840 growing degree days (GDD) base 42 and 2,502 GDD base 50. Temperatures will remain cool over the next few weeks with highs in the 50s and lows in the 40s or upper 30s.
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 the MSU Extension tree fruit team.
- Predicted apple harvest dates for 2023 from MSU Extension.
- More information on harvest management tools and timings can be found in this article.
- 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.
- Starch chart for Honeycrisp apples developed by Washington State University.
Maturity information for the west central region
Red Delicious
Fruit were sampled at two locations on Oct. 9 in Oceana County. Firmness is similar to last week at 17.0 pounds. Starch and sugar levels are also similar to last week. Fruit are mature and ready for harvest.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sept. 18 |
148 (156-138) |
92 (100-70) |
3.3 (4-3) |
18.0 (19.6-16.0) |
1.9 (3-1) |
10.6 (11.1-10.1) |
|
Sept. 25 |
148 (168-120) |
98 (100-80) |
1.5 (3-1) |
17.4 (19.4-15.8) |
2.9 (5-1) |
12.1 (13.4-10.4) |
|
Oct. 3 |
163 (169-158) |
93 (100-70) |
1.2 (3-1) |
16.7 (18.1-14.9) |
3.1 (8-2) |
12.5 (13.6-11.3) |
|
Oct. 9 |
170 (174-166 |
89 (100-80) |
1.0 |
17.0 (19.8-13.5) |
2.9 (4-2) |
12.5 (13.4-11.6) |
Idared
Idared samples were collected at three locations on Oct. 9 in Oceana County. Fruit weight increased from last week, and average fruit weight was at 197 grams. Red color is 86%. Background color is variable and is generally yellow green. Fruit firmness decreased to 14.9 pounds. Starch rating and sugars have increased and sugar levels are excellent. Fruit are ready for harvest according to the starch index below.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Sept. 25 |
186 (212-166) |
69 (98-40) |
3.6 (5-2) |
17.7 (19.3-16.4) |
2.9 (4-1) |
12.4 (12.9-12.0) |
|
Oct. 3 |
187 (204-153) |
79 (99-45) |
2.8 (4-1) |
15.4 (16.9-13.4) |
3.1 (5-2) |
12.1 (12.6-11.6) |
|
Oct. 9 |
197 (226-172) |
86 (99-55) |
2.6 (4-1) |
14.9 (16.5-12.9) |
4.9 (7-2) |
13 (13.5-12.6) |
Mutsu/Crispin
Fruit were sampled from two locations on Oct. 9 in Oceana County. Background color is generally green, and fruit have a slight blush. Fruit remain firm with an average firmness of 18.5 pounds. Sugar levels are excellent according to the Brix table below. Some blister spot and watercore were observed at a few orchard sites.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Oct. 3 |
239 (261-210) |
21 (50-0) |
4.1 (5-2) |
18.7 (22.4-15.5) |
3.7 (7-1) |
12.6 (13.8-10.5) |
|
Oct. 9 |
237 (270-204) |
40 (55-10) |
3.9 (4-2) |
18.5 (21.9-17.1) |
4.3 (7-2) |
14.7 (14.8-14.6) |
Aztec Fuji
Fruit were sampled from two locations on Oct. 9 in Oceana County. Red color development is at 89%. Background color, fruit firmness, starch clearing and sugar levels are similar to last week. Fruit are mature according to the starch chart and could be harvested for controlled atmosphere storage.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Oct. 3 |
203 (234-172) |
83 (99-50) |
3.7 (4-2) |
16.4 (18.7-14.6) |
4.1 (6-3) |
13.2 (13.3-13.1) |
|
Oct. 9 |
207 (222-193) |
89 (99-60) |
3.7 (4-3) |
16.5 (18.9-14.8) |
4.7 (7-2) |
13.1 (14.4-11.7) |
EverCrisp
Fruit were sampled from three locations on Oct. 9 in Oceana County. Red color development is improving at 74%. Background color is light green and fruit are firm with an average firmness of 21.0 pounds. Starch clearing is similar to last week and sugar levels have increased. Watercore was observed at all locations sampled this week.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Oct. 3 |
238 (273-193) |
65 (95-50) |
4.0 (5-3) |
21.4 (25.2-19.3) |
3.6 (6-1) |
15.7 (16.8-14.2) |
|
Oct. 9 |
267 (295-252) |
74 (90-50) |
3.6 (5-3) |
21.0 (24.0-18.3) |
3.2 (7-1) |
16.9 (17.6-16.0) |
Pink Lady
Fruit were sampled from two locations on Oct. 9 in Oceana County. Red color development is light and covering 60% of the fruit service. Background color is light green and fruit firmness is variable with an average firmness of 17.9 pounds. Starch clearing is higher than expected at this stage, and the starch average rating is 3.7. Sugar levels are excellent 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) |
|
Oct. 9 |
200 (230-170) |
60 (85-40) |
3.0 (4-2) |
17.9 (22.3-14.9) |
3.7 (5-1) |
14.7 (15.0-14.4) |
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 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 |
