West central Michigan apple maturity report – August 31, 2023
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EmailEarly apple varieties are being harvested this week in the west central region. This week has brought cool nights and great weather for red color development.
Apple maturity testing will occur weekly for the west central Michigan region beginning now through the end of harvest. Reports will be sent out every week following the Michigan State University Extension fruit team apple maturity calls on Wednesday mornings.
In the west central region, early varieties are being harvested which include Premier Honeycrisp, Zestar, Early Gold and Wildfire Gala. Minneiska, September Wonder Fuji and early strains of Gala are also showing signs of maturity development.
Weather update
Weather over the past week has been cool and dry. Daytime temperatures have been in the upper 60s and 70s, and nighttime temperatures have dipped down into the 40s. As of Aug. 31, the MSU Enviroweather station for Hart, Michigan, has accumulated 3,005 growing degree days (GDD42) and 1,966 GDD50. Rainfall has been in some locations over the past few weeks with only 0.16 inches in Hart on Aug. 29.
Expect hot and dry conditions going into next week. Another chance of rain is expected next Tuesday, Sept. 5, and highs will be in the 80s next week. Medium range forecasts indicate slightly warmer and drier conditions than normal.
How to read maturity tables
Each week, an apple maturity report will be provided and include average values for several apple samples for varieties nearing maturity. Maximum and minimum values are included in tables below 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. Samples were collected from two to four locations across Oceana County.
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 Extension.
- More information on harvest management tools and timings can be found in this article.
- Guidelines from MSU Extension 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.
Maturity information for the west central region
Premier Honeycrisp
Fruit were sampled from three locations on Aug. 28 in Oceana County. Individual samples represent fruit closest to maturity or first pick fruit in each block. Some growers are harvesting first pick this week. This variety is expected to harvest about three weeks before standard Honeycrisp strains. Red color and size improved over the past few weeks following cooler daytime temperatures and cool nights. Background color changed in early fruit to light yellow, indicating maturity, but some fruit still have green background color. Pressures are somewhat low, but Honeycrisp is typically not a very firm apple. Starch clearing varied widely across fruit with some fruit completely cleared.
A note about Premier Honeycrisp: Wait for acceptable varietal flavor and color to develop before picking. Picking fruit and getting it into the market early seems like an edge but will hurt repeat sales of this strain and standard Honeycrisp.
Bitter pit has been observed in some locations. Fruit that are high risk or are more susceptible to bitter pit development may be in blocks with younger trees, high-risk rootstocks or high-vigor trees. Large fruit are also more susceptible to bitter pit development than small fruit. High bitter pit-risk fruit should be cooled quickly to the recommended 38 degrees Fahrenheit storage temperature, as conditioning will exacerbate bitter pit. High risk fruit should be marketed as soon as possible. Fruit intended for longer storage should be pre-conditioned, with recommended conditions of 50 F (room temperature) for five to seven days.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 28 |
178 (151-201) |
72 (45-95) |
3.2 (4-2) |
13.2 (12-17) |
6.9 (4-8) |
14.7 (12-15) |
*Starch values according to the 1-8 SPI scale developed by Cornell.
RubyMac
Fruit was harvested from three locations in Oceana County. RubyMac is a red coloring strain of McIntosh and is at a similar stage of maturity to standard strains of McIntosh. Fruit are smaller than normal and dark red. Background color is 5 and very green. Average firmness is 16.4, and starch content is 2.6 Fruit is still immature, and sugar levels are good at this stage with Brix is 12.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 28 |
116 (148-84) |
87 (98-55) |
5 |
16.4 (14-21) |
2.6 (1-5) |
12.0 (11-13) |
Early Gala
Early strains of gala such as Brookfield and Pacific are expected to harvest approximately three weeks ahead of standard gala strains. For Wildfire Gala, the earliest strain, some growers have already completed first pick. Samples in the table below are for Brookfield and Pacific Gala. Many fruit are gaining red color, and background color is light green to yellow. Size has generally been reported as small for this variety, especially for trees with a heavy crop. The lack of rain this season has made sizing fruit challenging, even in irrigated blocks. Fruit are still firm. Starch is low but beginning to clear. Sugars are low at an average of 10.9 Brix.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 28 |
135 (131-141) |
59 (35-90 |
3.8 (2-5) |
21 (17-25) |
1.2 (1-2) |
10.9 (10-11.4) |
September Wonder Fuji
Fruit were sampled at two locations in Oceana County this week. Fruit are generally immature, but one location was more advanced in maturity than the other. Red color development is moderate, and background color is quite green. Starch is starting to clear and sugars are good.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 28 |
186 (172-201) |
62.4 (20-95) |
3.15 (2-4) |
15.3 (12-19) |
3.3 (2-5) |
14.4 (14-15) |
Minneiska
Fruit were sampled at three locations on Aug. 28 in Oceana County. Minneiska (SweeTango) is an early apple with bright color. Some growers have leaf pulled or summer pruned to enhance color development for this variety. Fruit are close to maturity and sugars are excellent. Red color development is increasing; however, some fruit have russet this season. Background color is also changing from light green to yellow. Starch is clearing into the cortex and sugar levels are at 14 Brix.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (Brix) |
|
Aug. 28 |
226 (163-188) |
20.2 (40-5) |
4.7 (5-4) |
15.8 (17.2-14.8) |
2.6 (4-1) |
11.6 |
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.
- Starch for Honeycrisp: will typically be rated using the standard Cornell SPI scale (1-8). However, a separate starch chart for Honeycrisp apples developed by Washington State University (scale 1-6) also exists.
- Brix = % sugar measured with Atago PAL-1 Pocket Refractometer.
Looking for more? View Michigan State University Extension’s Apple 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 |
|
Brix Guide |
Low |
Fair |
Good |
Excellent |
|---|---|---|---|---|
|
All varieties |
Less than 11 |
11 |
12 |
13 |
|
Honeycrisp |
Less than 12 |
12 |
12 |
Greater than 14 |