Grand Rapids area apple maturity report – September 25, 2024
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EmailSixth apple maturity report for the Grand Rapids region.
Crop update
Ambrosia, Jonagold, Red Delicious and Golden Delicious apples are currently mature. Aztec Fujis and Mutsu/Crispin apples are nearing maturity in the next week. Evercrisp was tested for the first time this week and is also almost mature.
High temperature impacts
Watercore can be exacerbated by high temperatures. Typically, high temperature watercore is around the periphery of the fruit instead of right in the core. Keep an eye out for watercore development as fruit head into storage.
The high temperatures this season has also shown up in sunburn around the state. Sunburn symptoms look like a reddened, sunken area on the apple that has a thin, pithy layer underneath the skin.
I am sampling internal ethylene this year. When reading those values, the percentage refers to the percent of sampled apples that exceeded 0.2 parts per million (ppm) internal ethylene. If over 50% of samples have this value, then they are ripening on their own and cannot be held back with stop-drop materials easily. Higher internal ethylene can have reduced long-term storage capacity. In practical terms, they should be prioritized for harvest.
Please keep in mind that stop-drop materials can be very useful to manage harvest windows during this early season, especially if color is a concern, but the window to effectively use them may be sooner rather than later.
This is a difficult harvest season to balance between harvest metrics like starch testing and internal ethylene and fruit quality like sugars and reddening. Stop-drop materials, reflective ground covers and summer pruning are being used effectively throughout the region to encourage color. Please keep in mind that waiting to harvest can impact the long-term storage and quality of the crop. Maintaining fruit quality and long-term integrity is crucial this year.
Some of these varieties coming into maturity are even exceeding the early predicted harvest dates by Michigan State University (MSU) this year. Frequent proactive sampling will be needed to stay on top of harvest. Please let me know if there are other varieties you would like me to sample.
Ambrosia
This variety was sampled at two locations in Kent County this week. The starch clearing is ideal for maturity right now. The sugar accumulation is excellent. The firmness (17.9 lbs) is still above the long-term controlled atmosphere (CA) recommendation of 17 lbs. This variety can quickly move from mature to overmature. I would recommend picking Ambrosia apples this week.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/16/2024 |
179.95 (151-244) |
73.33 (68.9-82.2) |
67.25 (30-85) |
1.85 (1-3) |
75% |
18.7 (16.81-21.84) |
3 (1-5) |
13.4 (12-16.2) |
|
9/23/2024 |
215.7 (137-286) |
76.435 (63.8-83.8) |
73 (35-95) |
1.15 (1-2) |
95% |
17.985 (15.06-21.1) |
4.1 (1-7) |
14.3 (13.8-15.6) |
Evercrisp
This variety was sampled at two locations in Kent County this week. Evercrisp will most likely be fully ripe next week. Starch clearing is at an average of 2 currently and the optimal for long term storage of Evercrisp is 2.5. The pressure is currently 24.93 lbs, which is a bit higher than the optimal 22 lbs for long-term CA storage. Given that the internal ethylene production is at 85% and the soluble solids are at 14.1, this variety will become mature quickly.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/23/2024 |
213.4 (128-306) |
76.825 (65.2-87.9) |
50.75 (25-75) |
2.7 (2-4) |
85% |
24.93 (21.47-32.3) |
2 (1-3) |
14.1 (13.1-15.1) |
Fuji
This variety was sampled at two locations in Kent County this week. The later season Fujis are now about a week away from maturity. The sugars and color are developing well. The internal ethylene increased sharply this week, which also indicates that main season Fujis are nearing maturity. The starch is at 2.5 this week, which is ideal for long-term storage. The firmness is at 19.97 lbs, which is still above the long-term CA storage recommendation of 18 lbs.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
8/20/2024 |
|
68.2 (59.4 - 74.5) |
43 (20 - 70) |
2.5 (2-3) |
|
22.4 (19.7 - 29.4) |
1.8 (1 - 2) |
9.1 (9 - 9.3) |
|
8/28/2024 |
147.2 (86-220) |
68.1 (60-79)
|
55.3 (30-90) |
2.3 (1-3) |
|
23.3 (20.4-27.7) |
2.1 (1-3) |
10 (9.4-11) |
|
9/3/2024 |
157 (122-201) |
70.2 (64.6-78.1) |
62.8 (35-85) |
2.3 (1-3) |
13% |
20.9 (18.7-25.6) |
1.9 (1-3) |
10.6 (10-13) |
|
9/9/2024 |
168.8 (117-246) |
71.3 (63.1-80) |
66.5 (30-85) |
2.3 (2-3) |
37% |
20.7 (17.76-25.67) |
2.3 (1-4) |
10.77 (10-12) |
|
9/16/2024 |
187.1 (108-275) |
73.9 (59.3-86.2) |
71.7 (45-90) |
2.6 (2-4) |
23% |
20 (17.25-26.92) |
2.2 (2-3) |
11.8 (10.8-12.8) |
|
9/23/2024 |
202.9 (198-281) |
74.91 (75.9-83.1) |
76.5 (75-90) |
2.1 (2-3) |
80% |
19.965 (17.69-22.46) |
2.55 (2-3) |
13.04 (11.2-15.1) |
Golden Delicious
This variety was sampled at one location in Kent County this week. This variety is currently mature across the different metrics and is being harvested around the area this week. The sugar accumulation and taste are excellent.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/16/2024 |
205.25 (137-287) |
75.71 (63.9-87.5) |
10.75 (0-30) |
2.6 (2-3) |
10% |
17 (14.43-21.44) |
5.05 (4-6) |
13.1 (11.2-15) |
|
9/23/2024 |
217.8 (175-286) |
77.24 (70-87.03) |
7 (0-20) |
1.6 (1-2) |
90% |
16.5 (13.7-18.4) |
6.2 (5-7) |
13.8 (13.1-14.2) |
Jonagold
This variety was sampled at one location in Kent County this week. This variety is being harvested around the area now. The firmness held from last week and is in line with the mid-long CA storage recommendations for this variety. The starch clearing is overmature. The sugar accumulation is excellent.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/16/2024 |
272.85 (164-391) |
84.45 (69.6-100) |
80.75 (65-95) |
1.4 (1-2) |
50% |
16.5 (14.42-21.06) |
6.1 (5-8) |
12.2 (11-14.8) |
|
9/23/2024 |
291.4 (224-377) |
86.94 (79.8-97.3) |
84 (75-90) |
1.1 (1-2) |
70% |
16.5 (13.8-20.1) |
6.7 (6-7) |
14.4 (12.8-17) |
Mutsu
This variety was sampled at one location in Kent County this week. The firmness and starch levels indicate that this variety will become ripe in the next week.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/16/2024 |
395.7 (334-507) |
93.7 (87.7-101.4) |
10.5 (0-35) |
1.9 (1-3) |
50.0% |
19.3 (15-22.8) |
2.6 (2-5) |
12.4 (11.6-13) |
Red Delicious
This variety was sampled at three locations in Kent County this week. The firmness is in line with the 18 lbs long term CA recommendation for Red Delicious. The starch clearing of 3.2 is close to the ideal 3.5 for maturity. The sugars have improved this week. Internal ethylene has significantly increased from last week. This variety is currently mature.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
9/16/2024 |
173.2 (99-285) |
70.1 (56.3-84.8) |
93 (85-100) |
1.03 (1-2) |
20% |
18.1 (15.11-22.42) |
2.6 (2-4) |
10.4 (9.2-14.2) |
|
9/23/2024 |
176.5 (133-265) |
70.95 (64.9-85.9) |
92.6 (85-100) |
1 (1-1) |
70% |
18.24 (13.94-21.09) |
3.2 (2-6) |
12.29 (11.2-14) |
For more information about regional reports, please visit the Michigan State University Extension website.