Grand Rapids area apple maturity report – September 18, 2024
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EmailFifth apple maturity report for the Grand Rapids region.
Crop update
Apples are flying off the trees right now. Any remaining Honeycrisp, Gala and McIntosh apples are wrapping up this week. Ambrosia, Jonagold and Golden Delicious apples are mature. Fuji and Red Delicious are nearing maturity in the next week.
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 optimal for controlled atmospheric (CA) storage. The sugar accumulation is excellent. The firmness (18.7 lbs) is still above the long-term CA recommendation of 17 lbs. This variety can quickly move from mature to overmature. I 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) |
Fuji
This variety was sampled at three locations in Kent County this week. The later season Fujis are now about a week away from maturity. While the starch clearing and firmness remain steady from last week, the sugar accumulation is increasing. The color is developing well.
|
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) |
Golden Delicious
This variety was sampled at two locations in Kent County this week. This variety is currently mature across the different metrics and should be harvested 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) |
Jonagold
This variety was sampled at two locations in Kent County this week. This variety is currently mature and should be harvested soon.
|
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) |
Red Delicious
This variety was sampled at three locations in Kent County this week. This variety is nearing maturity and should be looked at next week for harvest. The starch clearing and sugar accumulation should be a bit further developed prior to harvest.
|
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) |
For more information about regional reports, please visit the Michigan State University Extension website.