Northwest Michigan apple maturity report – September 6, 2023
Print
EmailApple maturity is moving along quickly across northwest Michigan, and early variety apple harvest is underway, including Premier Honeycrisp, Zestar, Ginger Gold and SweeTango.
This is the first apple maturity report for 2023 for northwest Michigan. Reports are sent out every week (usually on Wednesdays) following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.
We have been surprised at how quickly apple maturity has been moving along in our region of the state. Other apple growing regions in Michigan have not moved along as quickly as we have. In fact, much of our fruit maturity is in line with the Hart, Michigan, area. Growers are harvesting early varieties of apples, and many growers worked through the holiday weekend to get fruit off before this recent heat wave. Paula Reds were available in the region during the last week of August, and many growers with Premier Honeycrisp started to harvest those at this same time.
Growers with SweeTango and Zestar are also harvesting those fruits now. There is some russet showing up in SweeTango. Fruit size is variable, but there is smaller fruit out on the orchards from the dry conditions we had up until August. Even fruit that had irrigation in the blocks is a bit on the small size. Thinning strategies are making a particularly big impact on fruit size this year with the dry weather.
Fruit color is looking good for this time of the year; weather conditions before this recent heat were excellent for color development with the cooler days and nights. We have also noticed variability in firmness across different blocks. We have some small apples here at the Northwest Michigan Horticulture Research Center that are particularly hard while some larger sized fruit firmness is already down in the 17s.
Overall, fruit quality seems to be excellent. We are unsure of the impacts of this recent hot weather, but the weather is predicted to cool down from the 80-90s F daytime temperatures and the very warm conditions we have had overnight (the overnight low last evening was only 73.4F here at the NWMHRC).
Temperatures have been hot for the past two days but expected to cool toward this weekend. We have also had abundant sunshine over the holiday weekend. Today, Sept. 6, is the last day predicted to be in the mid-70s. Daytime highs are predicted to cool into the mid- to high 60s with overnight lows in the 50s. These conditions will be welcomed by apple pickers and will help improve color.
There is rain predicted for today and potential thunderstorms are also in the forecast. Despite a dry summer, we have had notable rainfall in August recorded at the Northwest Michigan Horticulture Research Center Enviroweather station:
- Aug. 2-3: 0.64 inch
- Aug. 11: 0.41 inch
- Aug. 14: 0.25 inch
- Aug. 17: 0.67 inch
- Aug. 28: 0.34 inch
How to read maturity tables
The majority of fruit were sampled from untreated blocks (no ReTain or Harvista applied).
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 maturity. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted.
For more information about apple maturity testing, review these resources compiled by the MSU Extension tree fruit team:
- Predicted apple harvest dates for 2023 from 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.
Honeycrisp
As mentioned above, many blocks of Premier Honeycrisp, an early strain of the Honeycrisp variety, have been harvested. Many growers started Premier harvest on Aug. 29, and the fruit was testing ripe and eating well. There has been local demand for Honeycrisp, and many growers jumped on the harvest wagon to deliver fruit to these local markets for the long weekend. Many growers spot-picked this early variety to optimize color.
The main strain of Honeycrisp is not yet ripe, but in our testing we had variability in starch removal. We had a range of starch removal from 2.9-5 with an average of 3.8. We also had quite a range in firmness, from 17-20.3. Brix readings were also quite variable among our five samples: 9.8 – 13.9 with an average of 11.5. Some of the riper fruit on the tree are eating pretty well given the range of maturity in the sampled apples.
|
Collection date |
Location |
Color |
Firmness |
Starch Index |
Brix |
|
9/5/2023 |
NWMHRC |
58.0% |
20.1 |
5 |
13 |
|
9/5/2023 |
NWMHRC |
48.5% |
20.3 |
4.1 |
13.9 |
|
9/5/2023 |
NWMHRC |
68.5% |
17 |
4.6 |
11 |
|
9/5/2023 |
Orchard 1 |
56.0% |
17.5 |
2.9 |
10.4 |
|
9/5/2023 |
Orchard 2 |
61.0% |
17 |
3.7 |
10.6 |
|
9/5/2023 |
Orchard 3 |
69.0% |
18 |
2.4 |
9.8 |
|
Average |
|
60.2% |
18.3 |
3.8 |
11.5 |
Gala
Gala is quite different than Honeycrisp as there is far less variability in the ripening parameters. The starch removal results are all testing in the 1s, with the lowest at 1.6 and an average of 1.4. There is variability in color, but one sample we collected was on bigger trees, and the color development is slow. Galas are still firm in the 20s.
|
Collection date |
Location |
Color |
Firmness |
Starch Index |
Brix |
|
9/5/2023 |
NWMHRC |
90% |
23 |
1.5 |
12.4 |
|
9/5/2023 |
Orchard 4 |
83% |
21 |
1.6 |
9.6 |
|
9/5/2023 |
Orchard 5 |
43% |
21.5 |
1 |
9.8 |
|
Average |
|
72% |
21.8 |
1.4 |
10.6 |
McIntosh
We also tested two blocks of Macs for maturity this week. It has become harder to find blocks of McIntosh for testing as this variety has been removed in recent years. Macs are not ripe and are eating green. The brix levels are looking good and testing in the 10s. The starch removal of our two samples both read 1.8 on the charts. As this variety is typically softer than other varieties, the firmness of these two samples ranged from 17.6 – 19.6.
|
Collection date |
Location |
Color |
Firmness |
Starch Index |
Brix |
|
9/5/2023 |
Orchard 4 |
85% |
17.6 |
1.8 |
10.2 |
|
9/5/2023 |
Orchard 6 |
67% |
19.6 |
1.8 |
10.7 |
|
Average |
|
76% |
18.6 |
1.8 |
10.5 |
Apple maturity sampling parameters
- Ethylene (% fruits with internal ethylene over 0.2 ppm) = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
- Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested. Indicates surface area covered in red and intensity of red color.
- Background color: 5 = Green, 1 = Yellow; 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
Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.
|
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 |
6 |
|
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 |
