Grand Rapids area apple maturity report – October 2, 2024
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EmailApple harvest is close to wrapping up. This is the seventh apple maturity report for the Grand Rapids region.
Crop update
Main season Fuji, Evercrisp and Red Delicious apples are currently mature. Braeburn and Pink Lady apples are up 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.
Ambrosia
This variety was sampled at one location in Kent County this week. This variety has been picked across most locations in the area. While firmness and sugar levels are similar to last week, the starch levels are continuing to progress and become more overmature. I would recommend picking this variety this week if you have not already.
|
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) |
|
9/30/2024 |
200.8 (159-247) |
74.6 (70.9-80.1) |
67 (30-90) |
1.3 (1-2) |
90% |
17.83 (14.85-21.34) |
4.7 (3-7) |
14.5 (13.8-15.2) |
Evercrisp
This variety was sampled at two locations in Kent County this week. Evercrisp is ripe. Starch clearing is at 2.5, which is in line with long-term storage recommendations for Evercrisp. The pressure is currently 24 lbs, which is a bit higher than the optimal 22 lbs for long-term controlled atmosphere (CA) storage. Given that the internal ethylene production is at 75% and the soluble solids are at 14.6, this variety is currently mature.
|
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) |
Fuji
This variety was sampled at four 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 3.7 this week, which is moving towards over maturity. The firmness is at 18.9 lbs, which is still a bit above the long-term CA storage recommendation of 18 lbs. This variety should be harvested 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) |
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 3.96 is above the ideal 3.5 for maturity. The sugars have improved this week. Internal ethylene has 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) |
|
9/30/2024 |
191.9(111-284) |
70.8 (60.3-80.4) |
90.9 (75-100) |
1 (1-1) |
80% |
18.5 (15.81-21) |
3.96 (2-7) |
12.9 (11-16) |
For more information about regional reports, please visit the Michigan State University Extension website.
