Grand Rapids area apple maturity report – October 9, 2024
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EmailApple harvest is wrapping up in the Grand Rapids area.
Crop update
Main season Fuji and Evercrisp apples are currently mature. Keep an eye on Granny Smith and Pink Lady next.
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.
Evercrisp
This variety was sampled at two locations in Kent County this week. Evercrisp is ripe this week. Starch clearing is holding at 2.5 which in line with long term storage recommendations for Evercrisp. The pressure is currently 21.4 lbs, which is in line than the optimal 22 lbs for longterm CA storage. Given that the internal ethylene production is at 100% and the soluble solids are at 15.6, this variety is currently mature. The coloring on this variety is not ideal this year, but otherwise the fruit quality is excellent.
|
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) |
|
9/30/2024 |
211 (117-322) |
76.4 (63.4-88.6) |
68 (40-90) |
2.5 (2-3) |
75% |
24 (21.3-26.84) |
2.5 (2-4) |
14.6 (13.2-15.8) |
|
10/7/2024 |
231.05 (156-350) |
79.23 (69.2-89.8) |
70.5 (45-85) |
1.9 (1-3) |
100% |
21.4 (19.42-24.76) |
2.5 (2-4) |
15.6 (14.3-17.2) |
Fuji
This variety was sampled at three locations in Kent County this week. The later season Fujis are now mature. The sugars and color are developing well. The internal ethylene is above the 50% threshold. The starch is at 4.4, which is becoming overmature. The firmness is at 17.6 lbs, which is a bit below the long CA storage recommendation of 18 lbs. This variety should be harvested this week. The total soluble solids have continued to increase with an average of 14.75 °Brix this week.
|
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) |
|
9/30/2024 |
201.2 (143-309) |
75.7 (67.3-87.1) |
75.2 (35-90) |
1.8 (1-3) |
60% |
18.9 (15.8-25.3) |
3.7 (1-6) |
13.4 (11.4-17.2) |
|
10/7/2024 |
209.1 (120-320) |
77.02 (64.2-89.8) |
70.5 (40-90) |
1.4 (1-2) |
100% |
17.6 (12.98-21.27) |
4.4 (3-8) |
14.75 (12.1-16.2) |
Granny Smith
This variety was sampled at one location in Kent County this week. While the sugars are fairly low for this variety, the firmness and starch indicate that this variety is mature.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
10/7/2024 |
267.8 (227-324) |
84.9 (80-89.1) |
7.5 (0-15) |
2.9 (2-3) |
0% |
17.6 (15.4-23.1) |
3.8 (3-5) |
11.5 (10.8-12.8) |
Pink Lady
This variety was sampled at one location in Kent County this week. While the firmness is still fairly high for this variety (compared to the recommended 18 lbs for long term CA storage), the starch and sugars indicate that this variety is now mature.
|
Collection Date |
Weight (g) |
Diameter (mm) |
Red Color (%) |
Background Color |
Ethylene (%) |
Firmness (lbs) |
Starch |
Soluble Solids (°Brix) |
|
10/7/2024 |
198.2 (147-232) |
74.6 (66.4-81.6) |
71.5 (60-85) |
1.6 (1-2) |
80.0% |
21.5 (16.7-28.45) |
4 (2-6) |
15.3 (14.2-16) |
For more information about regional reports, please visit the Michigan State University Extension website.