Grand Rapids area apple maturity report – August 10, 2022
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EmailEarly varieties are beginning to show signs of maturity in the Grand Rapids area.
This is the second maturity apple maturity report for 2022. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.
This week in the Grand Rapids, Michigan, area we are seeing the first signs of maturity in early varieties including Premier Honeycrisp, Paula Red, Ginger Gold and Zestar. Maturity is moving slowly, with little change from last week, and overall, most fruit are still green with little flavor developing. First picks may begin in about two weeks.
Weather last week included very hot, humid conditions. Temperatures were in the mid to upper 80s (degrees Fahrenheit) all week, with overnight lows remaining in the upper 60s. Relative humidity was near 90% for more than 12 hours on most days, and dew point temperatures were near 70 all week, which is highly unusual for our area.
As of Aug. 8, the Michigan State University Sparta Enviroweather station has accumulated 2669.0-degree days base 42 F (DD42). This is slightly above average, which is 2492.2 DD42, and approximately five days ahead of normal. Rainfall accumulation was significant in most places but somewhat variable, including between 0.5 - 1.0 inch on Wednesday night, followed by an additional 0.1-0.2-inch Sunday night into Monday. Presently, most of the Grand Rapids area is no longer experiencing drought conditions, although some areas in Newaygo and Ionia counties are still abnormally dry (D0) and some parts of eastern Michigan are under moderate drought conditions (D1), according to the U.S. Drought Monitor.
Expect cooler, fair, and very dry conditions for the remainder of the week through the weekend. This is thanks to the Canadian airmass and frontal boundary that finally moved into the area Tuesday night and Wednesday morning. High temperatures will be in the 70s. Lower overnight temperatures are likely to help with coloring of early varieties. Evapotranspiration is lower than we have been experiencing and what is normal for this time of year, due to the cooler temperatures. A slight chance of rain is possible over the weekend, but unlikely to result in significant accumulation. Cooler temperatures are expected to continue into next week.
How to read maturity tables
Each week, we test apple varieties that are nearing maturity in the Grand Rapids area. 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.
- Predicted apple harvest dates for 2022 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.
Zestar
Fruit is starting to color and seeds beginning to turn brown. Flavor is minimal and just starting to develop, sugars are still low. Some starch clearing just beginning. Excellent size. Fruit color is very bright and will improve with cooler nights.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Ethylene (% >0.2ppm) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Aug 1 |
170 (170-170) |
6.5 (15-5) |
5 (5-5) |
NT |
15.4 (17.6-14.1) |
2 (2-2) |
11 (11-11) |
|
Aug 8 |
180 (180-180) |
5.5 (10-0) |
4.8 (5-4) |
NT |
14.9 (18-13.7) |
1.8 (2-1) |
10.9 (10.9-10.9) |
Premier Honeycrisp
Early fruit beginning to show signs of maturity. First pick likely in about two weeks. Red color development just beginning, likely to improve with some cool night temperatures. Background color beginning to yellow and seeds beginning to turn brown in earliest fruit. Starch clearing also evident in some individual fruit, although most sampled fruit were still between 1-2 SPI. Flavor and sugars still less than ideal. It is important to remember that red color is not always a good indicator of maturity, internal parameters are better indicators. Cool weather over the next few days will likely improve color.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Ethylene (% >0.2ppm) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Aug 1 |
185 (210-160) |
5.75 (10-5) |
4.65 (5-4) |
NT |
20.225 (23.33-17.41) |
1 (1-1) |
10.9 (11.4-10.4) |
|
Aug 8 |
214 (240-180) |
5.2 (15-0) |
4.74 (5-3) |
NT |
18.32 (26.7-15) |
1.24 (6-1) |
10.4 (11.1-9.4) |
Paula Red
Red color coming along, background still very green. Very little change from last week. Fruit is sizing well. Starch clearing beginning, but sugars and flavor development are still just beginning. A small amount of watercore was evident in the samples we collected again this week. Pressures beginning to decrease.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Ethylene (% >0.2ppm) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Aug 1 |
170 (170-170) |
25 (30-0) |
4.7 (5-0) |
NT |
17.8 (22.21-15.19) |
1.6 (2-1) |
12.2 (12.2-12.2) |
|
Aug 8 |
210 (210-210) |
32 (45-20) |
4.7 (5-4) |
NT |
17.6 (21.9-15.4) |
2 (3-1 |
10.8 (10.8-10.8) |
Ginger Gold
Sizing well and a little starch clearing just beginning, but otherwise still very immature. Background still very green, sugar and flavor development just beginning.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Ethylene (% >0.2ppm) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Aug 1 |
185 (190-180) |
2.25 (5-0) |
4.6 (5-0) |
NT |
10.8 (25.1-19.1) |
1 (1-1) |
10.66 (10.8-10.5) |
|
Aug 8 |
203.3 (210-200) |
3.83 (50-0) |
4 (4-4) |
NT |
20.6 (25.1-18.2) |
1.1 (2-1) |
9.6 (10.6-8.2) |
Wildfire Gala
Beginning to show some signs of maturing. Red color coming along, background beginning to show some lightening. A little starch clearing evident in some fruit. Pressure still very high. Little sugar and flavor development. Seeds still white.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Ethylene (% >0.2ppm) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Aug 1 |
110 (110-110) |
32 (50-10) |
4.4 (5-4) |
NT |
20.03 (29.67-19.93) |
1 (1-1) |
9 (9-9) |
|
Aug 8 |
155 (160-150) |
33.25 (50-20) |
3.4 (4-3) |
NT |
21.45 (25.3-17.7) |
1.55 (4-1) |
9.85 (10.7-9) |
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 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 |
