West central Michigan apple maturity report – October 5 2022
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EmailVarieties such as Empire, Jonagold, Golden Delicious and Mutsu are being harvested this week in the West central region. Red Delicious and Idared are moving closer to maturity. Northern spy are still immature.
Apple maturity testing will occur weekly for the west central region beginning now through the end of apple harvest. Reports will be sent out every week, following the Wednesday morning Michigan State University Extension fruit team apple maturity calls.
In the west central region, growers are harvesting Jonagold, Rome and Empire. Some growers will also be harvesting Golden Delicious and Mutsu. Idared are showing signs of maturing this week. Northern spy are still immature. Apple harvest is moving steadily, and the crop load is excellent with more fruit on the trees than initially estimated. Red color continues to develop well with recent cool weather.
Weather over the past week has generally been cool and dry. There have been a few frosty mornings over the past few days across the region. Daytime temperatures have ranged from the 50s and 70s, and nighttime temperatures have ranged from the 30s to 50s. As of October 4, the Enviroweather station for Hart has reported an accumulation of 3695 DD42 and 2409 DD50
It has been a dryer week with little rain in the forecast, and we have had excellent picking weather. Slightly cooler temperatures are forecasted for the remainder of the week with highs in the 50s and 60s. Cool night temperatures are also forecasted this week with lows in the 40s and upper 30s. Cloudy conditions may moderate daily highs and lows which will help keep freezing temperatures at bay.
As fruit harvest continues, growers should consider applying preharvest fungicides to minimize storage rots.
How to read maturity tables
Each week, an apple maturity report will be provided and will 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 three locations across Oceana County.
For more information about apple maturity testing, review these resources compiled by Anna Wallis and Amy Irish Brown, MSU Extension.
- 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.
Maturity information for the west central region
Golden Delicious
Fruit were sampled from 3 locations on October 3 in Oceana County. Background color is transitioning from light green to more yellow. Many fruit have a pink blush. Fruit firmness varied from site to site with an average of 15.4. On average, starch clearing is 4.3, and sugars levels are excellent at 14.9 according to the Brix table below.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 19 |
191 |
16.3 |
3.1 (4-2) |
16.1 |
2.3 |
12.9 |
|
Sept 26 |
175 (183-168) |
29.2 (45-5) |
2.6 (4-1) |
15.5 (17.5-13.1) |
3.4 (6-1) |
13.9 (14.3-13.3) |
|
Oct 3 |
165 (168-163) |
30.5 (45-5) |
9.25 (16-2) |
15.4 (19.5-12.5) |
4.3 (6-1) |
14.9 (14.9-14.8) |
Red Delicious
Fruit were sampled from 2 locations on October 3 in Oceana County. Red color development is very good with most fruit being fully red. Fruit firmness varied from site to site with an average of 16.1. On average, starch clearing is low, but is reaching recommended clearing levels for maturity for this variety (2.5). Sugars levels are increasing and are considered fair according to the Brix table below. Some growers may pick this variety shortly depending on the intended storage time.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 19 |
204 |
91.4 |
5 (5-5) |
15.8 |
1.6 (2-1) |
10.3 |
|
Sept 26 |
190 (194-186) |
94.7 (100-90) |
1.7 (3-1) |
16.0 (18.2-14.1) |
1.8 (3-1) |
10.3 (10.7-9.9) |
|
Oct 3 |
190 (193-186) |
95.7 (100-85) |
1.4 (2-1) |
16.1 (17.7-13.3) |
2.3 (3-2) |
11.5 (12.4-10.5) |
Idared
Fruit were sampled from 3 locations on October 3 in Oceana County. Red color development is improving and is at 74.2% on average. Background color is similar to last week at a rating of 3.1. Fruit firmness decreased this week to 15.4 lbs. On average, starch clearing is low, and sugars levels are good according to the Brix table below. This variety is still fairly immature.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 26 |
211 (230-201) |
67.5 (90-50) |
3.1 (5-2) |
17.0 (18.9-13.0 |
1.3 (2-1) |
12.1 (13.2-11.5) |
|
Oct 3 |
194 (203-180) |
74.2 (90-60) |
3.1 (4-2) |
15.4 (18.1-13.3) |
2.2 (4-1) |
12.3 (12.4-12) |
Northern spy
Fruit were sampled from 2 locations on October 3 in Oceana County. Red color development is moderate at 65.5%. Background color is still quite green with an average rating of 3.8. Fruit are very firm with an average of 18.9 lbs. On average, starch clearing is 4.2, and sugars levels are excellent for this variety.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Oct 3 |
228 (241-217) |
65.5 (90-45) |
3.8 (5-3) |
18.9 (25.4-12.8) |
4.2 (8-1) |
14.5 (14.8-14) |
Mutsu
Fruit were sampled from two locations on Sept. 26 in Oceana County. This variety is still immature. Background color is light green, and some fruit have a light pink blush. Fruit firmness varied from site to site with an average of 17.0. On average, starch clearing is low, and sugars levels are good according to the Brix table below.
|
Collection Date |
Fruit Weight (g) |
Red Color (%) |
Background color (5-1) |
Firmness (lbs) |
Starch (1-8) |
Soluble Solids (°Brix) |
|
Sept 26 |
242 (256.5-227.5) |
31 (50-20) |
5 (5-3) |
17.0 (20.1-14.5) |
1.5 (2-1) |
11.7 (12.7-10.6) |
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 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 |
|
Brix Guide |
Low |
Fair |
Good |
Excellent |
|
All varieties |
Less than 11 |
11 |
12 |
13 |
|
Honeycrisp |
Less than 12 |
12 |
12 |
Greater than 14 |