Grand Rapids area apple maturity report – September 20, 2023
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EmailGrowers are picking Gala this week. Honeycrisp is right around the corner.
This is the second Grand Rapids, Michigan, area apple maturity report for the 2023 harvest season. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.
Gala harvest is well underway in the Grand Rapids area. Fuji and McIntosh strains are also mature this week and can be picked. Honeycrisp maturity is faster than expected this season. Starches have been clearing faster than sugar accumulation throughout Michigan for Honeycrisp this year. If color development is appropriate, Harvista applications can slow down maturity.
- 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.
How to read the maturity tables
Each week, we test apple varieties that are nearing maturity in the Grand Rapids region. We are reporting average values for several samples for each variety. Maximum and minimum values are included for the highest and lowest individual fruits evaluated for each to give a full spectrum of the maturity.
Updates for this week
Weather
Temperatures this week (Sept. 11-18) have averaged in the high 50s with daily lows between 45.1 and 54.7 degrees Fahrenheit and daily highs between 62.8 and 70.8 F. We are anticipating a climb in temperatures later this week between Thursday and Sunday with highs around 80 F. The cool nights this past week have been excellent for color development.
The MSU Enviroweather station for Sparta has reported an accumulation of 3,629.7 growing degree days (GDD) base 42 F and 2,399 GDD base 50 F as of Monday, Sept. 18. The last precipitation event recorded at the MSU Enviroweather station at Sparta was Monday, Sept. 11 (0.55 inches) and Tuesday, Sept. 12 (0.02 inches).
There is a potential rain event this Wednesday, Sept. 20. Please keep in mind that rain events over 2 inches can wash off fungicide residues on fruit. Maintaining fungicide coverage at this point in the season is important to minimize late season rots, especially in long-term storage.
Variety reports
Ambrosia
Ambrosia apples were collected at one location in Kent County this week. While the starch is still very present, these apples are close to full maturity. The red coloration is well developed and the background color is very yellow. The fruit firmness has decreased and the sugars have increased this past week. Keep in mind that Ambrosia is chilling sensitive and apples harvested at late maturity are more likely to develop soft scald and brown in storage.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
118.5 |
62.45 |
48 |
- |
26.82 |
1.2 |
9.54 |
|
9/18/23 |
164.2 (121-216) |
70.63 (62.5-78.26) |
75.5 (50-90) |
1 (1-1) |
19.98 (17.18-23.1) |
1.4 (1-3) |
11.23 (9.5-12.3) |
Cortland
Cortland apples were sampled from one location in Kent County this week. The color is nicely developed in this sample. The fruit firmness and starch clearing are progressing well. The sugars need to continue to accumulate prior to full maturation.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/18/23 |
146.2 (121-175) |
73.26 (69.3-78.24) |
87 (80-95) |
1.6 (1-2) |
16.12 (13.49-18.12) |
3 (2-5) |
9.65 (7.5-11.8) |
Fuji
Fuji apples were sampled at two locations this week in Kent County. The firmness, starch clearing and sugar accumulation are in line with maturity for this variety.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
157.3 |
74.1 |
52.5 |
- |
20.93 |
3.4 |
8.17 |
|
9/18/23 |
181.15 (122-236) |
75.141 (67.57-80.19) |
72.25 (30-90) |
1.725 (1-2) |
15.88 (11.75-22.17) |
4.9 (1-8) |
10.55 (8.7-12.4) |
Gala
Gala apples without ReTain were sampled at one location this week in Kent County. The firmness and starch clearing associated with this sample is in line with full maturity. The sugar accumulation is still lagging somewhat behind. Gala harvest is a priority in the region currently.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
152.1 |
68 |
76.3 |
- |
19.44 |
6.35 |
9.3 |
|
9/18/23 |
160.8 (109-188) |
70.72 (62.7-75.63) |
62 (30-80) |
1.1 (1-2) |
15.53 (12.48-18.52) |
6.3 (3-8) |
9.95 (7.8-11.4) |
Gala with ReTain
Gala apples with ReTain applied were sampled at two locations this week in Kent County. These samples had comparatively less starch clearing (5 versus 6.3) and higher firmness (18.5 versus 15.53) than the untreated Galas. The visual difference between the treated and untreated Galas can be noted in the picture above.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
170.46 |
70.95 |
68.83 |
- |
22.56 |
3.02 |
9.54 |
|
9/18/23 |
157.4 (88-275) |
69.52 (58.14-86.5) |
84.25 (35-95) |
1.45 (1-2) |
18.5 (14.34-24.36) |
5 (1-7) |
10.15 (8.8-11.5) |
Honeycrisp
Honeycrisp apples were collected at two locations in Kent County this week. These samples had a wide range of sugars (9.7-13.6), but a lower average sugar accumulation than anticipated (10.55). The starch clearing is well progressed with samples ranging from 6-8. Sugar accumulation lagging behind starch clearing has been consistent across the state for Honeycrisp this year. At this point in the season, Harvista applications to slow down maturity could be useful if the color is well developed.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
182.7 |
74.1 |
74.75 |
- |
17.9 |
7.4 |
10.15 |
|
9/18/23 |
161.6 (132-289) |
72.65 (68.7-89.6) |
75.25 (30-95) |
1.8 (1-3) |
13.12 (11.19-14.56) |
7.2 (6-8) |
11.11 (7-13.1) |
Jonathan
Jonathan apples were sampled at two locations this week in Kent County. The parameters are in line with a fully mature sample.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/12/23 |
64.58 |
64.58 |
95.5 |
- |
21.05 |
4.4 |
8.61 |
|
9/18/23 |
213.75 (91-333) |
77.11 (60.44-92.29) |
83 (20-100) |
1.45 (1-2) |
15.53 (13.9-18.49) |
3.35 (2-7) |
11.11 (7-13.1) |
McIntosh
McIntosh apples were sampled from two locations this week in Kent County. The strains sampled include RubyMac and standard McIntosh. Starch clearing and sugars are rising while firmness has dropped. McIntosh now falls within all maturity parameters.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
9/12/23 |
116.3 |
66.36 |
90.5 |
- |
26.59 |
4.9 |
9.44 |
|
9/18/23 |
128.95 (96-192) |
68.67 (63.2-95) |
90.5 (65-100) |
1.67 (1-2) |
14.14 (11.99-17.33) |
5.4 (4-7) |
11.71 (9.4-12.6) |
Red Delicious
Red Delicious apples were sampled at one location in Kent County this week. The color development is well progressed. The firmness is in line with mid-controlled atmosphere storage. The sugar accumulation and starch clearing are close to full maturity.
|
Collection Date |
Fruit Weight (g) |
Diameter (mm) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
9/18/23 |
154.8 (117-175) |
69.63 (62.46- 74.32) |
88 (75-100) |
1.4 (1-2) |
17.56 (16.13-19.25) |
2.1 (1-4) |
10.56 (9.9-12.2) |
Apple maturity sampling parameters
- % 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
- 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.
- 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.
|
Brix Guide |
Low |
Fair |
Good |
Excellent |
|---|---|---|---|---|
|
All varieties |
Less than 11 |
11 |
12 |
13 |
|
Honeycrisp |
Less than 12 |
12 |
12 |
Greater than 14 |
|
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 |
