Northwest Michigan apple maturity report – September 4, 2024
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EmailAll apple varieties tested this week are moving toward maturity. The weather is looking good for color development.
General comments
Apples are early again this year, and growers should be ready to harvest as soon as their fruit is mature. As repeated in last week’s maturity report, it has been surprising to see just how early fruit are maturing. Of the eight Honeycrisp samples tested, the overall maturity averages just over 3 for starch removal, and Gala and McIntosh are testing in the 2 range.
In an overview of all the starch removal readings from all varieties this week, it looks like all varieties will mature at a similar time. We may see some separation between varieties as the weather becomes more variable, but again, growers need to be able to jump on harvest as soon as fruit is ripe on their farm.
Growers also need to be using Retain or Harvista to help manage harvest timing, and these tools may be critical in a year when all fruit is ripening at a similar time. These materials have been shown to be excellent to hold fruit if harvest runs longer or slower than anticipated. Amy Irish-Brown of Valent has sent out excellent advice in her newsletter: “Right now, we are in that 14-day ReTain use window to stick fruit and get pre- and post-harvest benefits in the Grand Rapids area, and temperatures are ideal for ReTain applications. Consider applications now before the heat moves back in next week for best results.” I would maintain that we are at a good timing for such applications in northwest Michigan as well, and again, I would highly recommend using these plant growth regulator (PGR) tools in a compressed and early season.
Weather forecasts are predicted to be warm and sunny through this week, and overnight temperatures are forecasted to drop into the high 40s and low 50s. On the first day of school, I dropped off at 8 a.m. to the car thermometer reading 45 degrees Fahrenheit, and when I drove back up from Manistee County at 2:30 p.m., it was 75 F—a 30-degree swing! These conditions are excellent for coloring up apples. Apple color has improved in the last week. Temperatures are predicted to be cool and wet over the weekend, but more hot weather is on the way next week. Conditions are also dry across the region, and we have not had significant rain since Aug. 15-17 where we received 1.16 inches of rain at the Northwest Michigan Horticulture Research Center.
This is the second official week for apple testing in northwest Michigan. Reports are sent out on Wednesday every week, following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.
- Predicted apple harvest dates for northwest Michigan 2024 from Michigan State University (MSU).
- More information on harvest management tools and timings can be found in this article.
- Guidelines from MSU 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 northwest Michigan. 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.
Ginger Gold
Ginger Gold harvest is underway. This variety has good size, and the firmness is holding for our few samples. This variety is typically one of the earliest we pick in northern Michigan, and similar to last week, the maturity seems slower compared to other varieties. Most of the typical spots where we collect Ginger Gold samples have been harvested.
Honeycrisp
Honeycrisp firmness remains similar from last week to this week, perhaps dropped a bit, but still consistent with the last few weeks. Again, we heard comments on the MSU team call that firmness in this variety may be an issue. Color in most Honeycrisp blocks has improved over this past week. Our color ranges from 40-95% with an average of 75%. These forecasted weather conditions will continue to improve color. Brix has increased almost 1% from last week. Starch removal is up one from 2.1 last week to an average of 3.2 this week. Growers need to be actively managing this important variety with PGRs to balance good color, letting fruit hang and harvest timing.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-6) |
Soluble Solids (% Brix) |
|---|---|---|---|---|
|
20-Aug |
54.3% (15-85) |
19.5 (17-23) |
1.2 (1-5) |
10.1 (9-11.4) |
|
27-Aug |
57.5% (15-95) |
20.5 (17.5-23) |
2.1 (1-6) |
11.3 (9.1-12.9) |
|
3-Sept |
74.6% (40-95) |
19.0 (15.5-23.5) |
3.2 (1-7) |
12.1 (9.5-14.6) |
Gala
Gala size is still quite variable across blocks. Color has also improved in this variety over the past week, and the range of color is between 50-100%. Galas are still testing very firm with an average of 22.3 this week. Starch is still testing in high 1 range, but we did have samples from one block that are testing at a starch removal of 4. Brix in Gala are also still quite low, and some apples are testing out with a brix of 10.7, which is the same as last week.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-6) |
Soluble Solids (% Brix) |
|---|---|---|---|---|
|
20-Aug |
58.8% (30-100) |
22.6 (19.5-23.5) |
1 (1-1) |
9.6 (8.2-11.1) |
|
27-Aug |
73.3% (25-100) |
22.55 (20-23) |
1.6 (1-7) |
10.7 (8.3-11.9) |
|
3-Sept |
82.5% (50-100) |
22.3 (19-23) |
1.9 (1-4) |
10.7 (9.2-13.8) |
McIntosh
We have few McIntosh blocks near the research station, and most trees are big with older strains of Macs. Color is variable, likely as a result of the particular strain. However, overall color has improved since last week. Firmness is still quite good in this typically softer variety. Starch removal has not changed over the past week, and brix is low with some variability.
|
Collection Date |
Red Color (%) |
Firmness (lbs) |
Starch (1-6) |
Soluble Solids (% Brix) |
|---|---|---|---|---|
|
20-Aug |
59.3% (25-90) |
20.6 (18-23) |
1.2 (1-2) |
9.8 (8.4-11) |
|
27-Aug |
69.25% (25-100) |
21.7 (19-23) |
1.4 (1-3) |
10.25 (8.3-12.3) |
|
3-Sept |
65.5% (5-100) |
19.3 (16-23) |
2.1 (1-4) |
11.1 (8.2-12.4) |
Apple maturity sampling parameters
- Color % = the visual percentage of red color from 0 to 100; 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
|
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 |
7 |
|
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 |
Be sure to check out our MSU Starch Index Chart!
