West central Michigan apple maturity report – September 25, 2024

Golden Delicious and Red Delicious are being harvested in the west central region this week. Temperatures are cooler this week, and growers are working around the rain to harvest fruit.

Aztec Fuji apple tree.
Figure 1. Aztec Fuji in Oceana County on September 23. Photo by Reilly Ford.

In the west central region, Rome have been harvested at some locations. Harvest of Golden Delicious, Red Delicious and Idared began this week. These varieties as well at Mutsu, Ambrosia and Aztec Fuji were tested for maturity this week (Figure 1).

Weather over the past week has been cooler with temperatures closer to normal for this time of year with highs in the 70s and 60s. High temperatures will remain in the 60s and 70s over the next week with lows in the 50s. Storms brought rain to the region on Sept. 24 and 25. Rain is welcome because it has been so dry; however, excessive rain has led to a slowdown in harvest for some orchards in the region. According to Michigan State University Enviroweather stations, rainfall amounts varied widely across the region where Ludington received 1.12 inches of rain over the past few days, and the Fremont area received 3 inches of rain or more.

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 five locations across Oceana County (Figures 2-3).

Ambrosia, Golden Delicious, Idared, Red Delicious and Aztec Fuji apples.
Figure 2. Ambrosia, Golden Delicious, Idared, Red Delicious and Aztec Fuji fruit in west central Michigan on September 23. Photo by Reilly Ford.

For more information about apple maturity testing, review these resources compiled by the Michigan State University Extension tree fruit team.

Maturity information for the west central region

Several varieties of apples in containers ready to be tested for maturity.
Figure 3. Starch staining for apple varieties harvested on September 23. Photo by Emily Lavely.

Mutsu/Crispin

Fruit were sampled at two locations in Oceana County this week. Fruit are still immature and have had little change in maturity over the past few weeks. There is some blush although fruit are still green. Background color is light green, and firmness is similar to last week at 19.4 lbs pressure. Starch is 2.0, and sugars improved from last week to 13.2 degrees Brix. Watercore was observed at both locations this week.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 9

301 (343-259)

25 (45-2)

4.8 (5-4)

18.6 (21.5-16.1)

1.9 (3-1)

11.3 (11.5-11.1)

Sept 16

328 (346-311)

31 (50-0)

4.7 (5-4)

18.8 (21.1-17.0)

2.2 (7-1)

12.3 (12.9-11.7)

Sept 23

368 (373-364)

30 (50-0)

4.2 (5-3)

19.4 (23.3-16.1)

2.0 (3-1)

13.2 (13.8-12.6)

Golden Delicious

Fruit were sampled at four locations in Oceana County this week. Fruit are mature at some locations and fruit are being harvested this week. Some fruit have blush, and background color is light green. Firmness is the same as last week at 16.9 lbs pressure, and recommended pressure for long-term storage is 17. Starch is 3.6, and fruit are considered mature at a starch rating of 3. Sugars have increased and are excellent at 14.4 Brix according to the table below.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 9

170 (190-142)

27 (60-0)

4.0 (5-2)

18.0 (21.0-15.1)

1.7 (4-1)

12.5 (12.6-12.3)

Sept 16

190 (250-158)

28 (50-0)

3.7 (5-2)

16.9 (22-12.8)

2.9 (5-1)

13.0 (13.9-12.0)

Sept 23

192 (256-155)

25 (90-0)

3.5 (5-1)

16.9 (26.9-13.9)

3.6 (6-2)

14.4 (15.4-13.9)

Red Delicious

Fruit were sampled at three locations in Oceana County this week. Fruit are mature at some locations, and red color development is at 98%. Background color is yellow green, and firmness is down slightly from last week at 16.8 lbs pressure. Pressure recommended for long-term storage is 18 lbs. Starch is 2.1, and sugars are 10.6 Brix. Red delicious are considered mature with a starch rating of 2.5.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 9

151 (180-122)

98 (100-95)

1.4 (3-1)

18.2 (21.9-16.0)

1.4 (2-1)

10.0 (10.3-9.7)

Sept 16

165 (179-156)

97 (100-70)

2.2 (4-1)

17.7 (20.5-16.2)

1.7 (5-1)

10.3 (11.2-9.7)

Sept 23

167 (203-128)

98 (100-90)

2.2 (4-1)

16.8 (17.9-15.6)

2.1 (4-1)

10.6 (11.2-10.2)

Idared

Fruit were sampled at five locations in Oceana County this week, and harvest of this variety has begun at some orchards. Fruit are immature on average, but maturity varied from site to site. Red color development is 86%. Background color is light green, and firmness is 17.4 lbs pressure. Pressure recommended for long-term storage is 16 lbs, and fruit are considered mature with a starch rating of 3.5. Starch is rated at 2.6. Sugars improved from last week and are considered good at 12.6 Brix.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 16

197 (260-167)

75 (99-50)

3.7 (4-3)

18.4 (21.6-14.3)

1.9 (3-1)

11.4 (12.4-10.6)

Sept 23

191 (240-162)

86 (99-50)

3.5 (4-1)

17.4 (20.6-13.2)

2.6 (4-1)

12.6 (13.7-11.8)

Ambrosia

Fruit were sampled at two locations in Oceana County this week. Fruit are mature although there was site to site variation for maturity metrics. Red color development is at 66%, and fruit have a beautiful pink blush. Background color is light green, and firmness is 17.0 lbs pressure. Starch is 3.5, and sugars improved from last week to 12.5 Brix.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 16

220 (255-186)

56 (70-40)

3.2 (4-3)

18.2 (23.3-15.1)

2.2 (5-1)

11.6 (12.4-10.7)

Sept 23

217 (229-206)

66 (90-45)

2.5 (4-1)

17.0 (21.3-13.8)

3.5 (7-1)

12.5 (13.8-11.2)

Aztec Fuji

Fruit were sampled at three locations in Oceana County this week. Fruit are immature, but they are more mature than expected and ahead of normal this year. Fruit may be mature and ready for harvest next week for long- or mid-term storage. Red color development is 83%, and background color is green. Firmness is 17.5 lbs pressure. Starch is 2.5, and sugar is excellent at 13.1Brix.

Collection Date

Fruit Weight (g)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-8)

Soluble Solids (°Brix)

Sept 23

205 (231-188)

83 (99-60)

4.1 (5-3)

17.5 (19.3-16.1)

2.5 (4-2)

13.1 (14.0-12.6)

Apple maturity sampling parameters

  • 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 for Honeycrisp: will typically be rated using the standard Michigan State University starch 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

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