Grand Rapids area apple maturity report – Sept. 22, 2021

This is the seventh apple maturity report for the Grand Rapids, Michigan, region.

Apple cut in half with iodine on the flesh.
An Empire apple stained with iodine. Some Empire fruit are already showing considerable starch clearing, and overall maturity is a little earlier than normal. This is a common observation in most samples tested this week. Photo by Anna Wallis, MSU Extension.

This is the seventh apple maturity report for the 2021 harvest season. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

For general information about how samples are collected and processed, please refer to Apple Maturity Report #1.

How to read the maturity tables

For each variety evaluated, we provide data from our evaluations in a table. In each, a row is provided for each sample tested. This allows you to see how the varieties may be progressing in different regions or specific locations. An average is included 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. Recommended values are included for each variety at the bottom of the table. These suggested values for firmness and starch index were also published in a standalone table format. Firmness ranges encompass long and short-term storage recommendations.

Updates for this week

Weather – Happy first day of Autumn! In the Grand Rapids, Michigan, area this week, the changing of the season is noticeable in the weather. We are experiencing significantly cooler weather, with highs in the 60s and low 70s degrees Fahrenheit and lows dipping into the 40s some nights. Rainfall Tuesday evening led to accumulation of approximately 0.2 inches in Sparta, Michigan, with more or less throughout the Grand Rapids area. More rain is expected for the remainder of the week, with possible accumulation of greater than 1 inch.

Despite the cooler weather, warmer conditions leading up to harvest have resulted in early maturity and less effect of stop-drop PGR products in many locations. It is very important to be testing fruit earlier than normal to detect fruit that is maturing ahead of expected times. In our testing, we have started testing fruit considerably earlier than normal for a number of varieties. In these, we are often seeing starch clearing beginning, ethylene development, pressures dropping sooner than we would have in a normal year. Evercrisp and Fuji this week are examples.

Gala harvest is complete for untreated fruit. Many treated fruit are also finishing harvest.

Honeycrisp harvest is complete or underway now.

Jonagold, Jonathan and Empire untreated fruit are entering the harvest window over the next week.

Golden Delicious, Red Delicious and Ida Red are showing signs towards ripening and should be watched closely.

Ambrosia internal qualities show fruit are mature, but color is less than excellent.

Evercrisp, Fuji and Rome are still very immature, but showing the first signs of ripening.

Predicted harvest dates according to the Maturity Model in Enviroweather are about 10 days earlier than normal for early varieties (Gala, Honeycrisp, McIntosh). At this time, the season appears to be between five and seven days ahead of normal.

Mixed maturity is evident in most varieties and locations. Multiple picks may be needed to harvest fruit at the appropriate maturity for successful storage conditions.

Empire

This variety is entering the harvest window now or will be in the next week. Starch clearing and ethylene production are well underway. Pressures are beginning to decrease to an acceptable level in some places but are still very high in other locations—this is an important indicator for this variety, as a softer fruit typically used for processing. Sugars are in an acceptable range. Model-predicted harvest date was Sept. 22 for this variety and they seem to be coming in right on target. Fruit treated with AVG or 1-MCP is delayed as expected.

Empire sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Empire

Belding3

180

40%

39.0

3.0

16.0

4.3

10.1

Empire

Ridge1

170

0%

32.5

3.0

16.9

3.8

10.8

Empire

Ridge2

151

50%

.

.

18.8

3.4

12.9

Empire

Ridge7

180

0%

84.0

3.0

18.5

3.3

14.2

Empire

Ridge8

155

10%

.

.

19.0

3.1

13.8

Average

 

167

20%

51.8

3.0

17.8

3.6

12.4

Max

 

 

 

90.0

3.0

21.9

6.0

14.2

Min

 

 

 

10.0

3.0

14.3

1.0

10.1

Recommended

 

 

 

 

 

14-16

3.5-6

 

Empire weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

.

0%

93.0 (85-100)

1.6 (2-1)

19.6 (16.8-22.8)

2.2 (2-4)

13.0 (13.0-13.0)

20-Sep

167

20%

51.8 (10-90)

3 (3-3)

17.8 (14.9-21.9)

3.6 (1-6)

12.4 (10.1-14.1)

Jonagold

The earliest harvest window is just beginning to peak open for Jonagold. In some places, fruit is ready for processing. Color is less than excellent in most places, although a few locations or fruit at the end of rows are coloring nicely. Background color is changing from green to yellow noticeably. Harvest is expected to begin for most locations in the next week to 10 days. Model predicted harvest was Oct. 1, but we expect actual harvest to be slightly earlier where color is adequate and crop load is light

Jonagold sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Jonagold

Ridge2

236

90%

.

.

15.7

5.5

14.2

Jonagold

Ridge3

267

90%

.

.

19.0

5.3

15.4

Jonagold

Ridge4

257

50%

.

.

17.1

5.9

13.0

Average

 

253

77%

.

.

17.3

5.6

14.2

Max

 

 

 

.

.

22.0

8.0

17.0

Min

 

 

 

.

.

13.5

3.0

12.0

Recommended

 

 

 

 

 

15-17

3.5-5.5

 

Jonagold weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

245

27%

28.7 (10-60)

2.7 (4-2)

19.3 (14.0-26.1)

4.0 (2-7)

13.1 (12.4-13.9)

20-Sep

253

77%

.

.

17.3 (13.5-22.0)

5.6 (3-8)

14.2 (12.0-17.0)

Jonathan

This variety is also showing signs of maturity Ethylene production is increasing in all samples, firmness is beginning to come down, and sugar content is increasing quickly. Starch clearing is very high in a few fruit, and majority of fruit are about a week or ten days ahead of the recommended window for picking. Model predicted harvest was Oct. 1, but we expect actual harvest to be very close to that day or slightly earlier as processors demands see fit.

Jonathan sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Jonathan

Ridge2

190

60%

.

.

17.1

2.6

13.2

Jonathan

Ridge3

173

20%

.

.

18.0

2.3

13.1

Jonathan

Ridge4

199

10%

.

.

15.9

3.1

11.3

Average

 

188

30%

.

.

17.0

2.7

12.5

Max

 

 

 

.

.

20.5

7.0

15.0

Min

 

 

 

.

.

14.8

2.0

12.0

Recommended

 

 

 

 

 

14-16

3.5-5.5

 

Jonathan weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

150

60%

89.0 (75-100)

2.2 (3-1)

17.5 (14.9-19.2)

4.0 (1-8)

12.7 (12.3-13.0)

20-Sep

188

30%

.

.

17.0 (14.8-20.5)

2.7 (2-7)

12.5 (12.0-15.0)

Golden Delicious

This variety is very close to the harvest window and moving very quickly. Color is improving from green to yellow in most location and size is very good. Minimal red color was observed, with only a touch of blush on a few fruit. Evaluation of starch clearing, firmness, and sugars all indicate fruit is very close to harvest and should likely begin picking within the week. Flavor of fruit is also showing noticeable development. Our predicted harvest date for Goldens was Oct. 1 and that date seems to be a bit on the late side according to the fruit we are testing. Many Golden blocks have a light crop load and could ripen faster than expected. There is very little red cheek color at this time.

Golden Delicious sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Golden Delicious

Ridge2

163

10%

.

.

16.7

5.3

13.4

Golden Delicious

Ridge3

194

20%

.

.

17.7

2.8

13.4

Golden Delicious

Ridge4

202

10%

.

.

17.6

2.6

14.0

Average

 

186

13%

.

.

17.3

3.6

13.6

Max

 

 

 

.

.

19.5

6.0

15.0

Min

 

 

 

.

.

14.8

2.0

12.0

Recommended

 

 

 

 

 

15-17

3-6.5

 

Golden Delicious weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

185

7%

.

2.6 (3-2)

18.6 (13.8-24.9)

2.5 (1-6)

13.0 (12.4-13.7)

20-Sep

186

13%

.

.

17.3 (14.8-19.5)

3.6 (2-6)

13.6 (12.0-15.0)

Red Delicious

This variety appears to be maturing quickly, but it will often do this and then stall out. Ethylene development is evident in many samples with some over the 0.2 ppm climacteric. Pressures, starch and sugars are just beginning to approach acceptable harvest windows. Model predicted harvest was Oct. 7 for this variety but we expect actual harvest to be slightly earlier. Keep a close eye on Red Delicious.

Red Delicious sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Red Delicious

Ridge2

190

60%

.

.

17.1

2.6

13.2

Red Delicious

Ridge3

173

20%

.

.

18.0

2.3

13.1

Red Delicious

Ridge4

199

10%

.

.

15.9

3.1

11.3

Average

 

188

30%

.

.

17.0

2.7

12.5

Max

 

 

 

.

.

20.0

5.0

14.5

Min

 

 

 

.

.

15.0

2.0

11.0

Recommended

 

 

 

 

 

16-18

2.5-6

 

Red Delicious weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

190

40%

89.0 (75-100)

2.2 (3-1)

18.1 (16.0-21.0)

2.3 (2-3)

11.5 (10.9-12.0)

20-Sep

190

30%

.

.

17.0 (15.0-20.0)

2.7 (2-5)

12.5 (11.0-14.5)

Idared

This variety is showing signs of maturity but still needs a little more time. Model predicted harvest was Oct. 7, but we expect actual harvest to be slightly earlier.

Idared sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Idared

Ridge2

153

0%

.

.

17.8

3.5

12.8

Idared

Ridge3

178

80%

.

.

19.3

2.0

10.6

Idared

Ridge4

177

40%

.

.

19.8

1.7

12.6

Average

 

169

40%

.

.

19.0

2.4

12.0

Max

 

 

 

.

.

24.0

5.0

13.0

Min

 

 

 

.

.

15.0

1.0

12.0

Recommended

 

 

 

 

 

14-16

3.5-6

 

Idared weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

150

37%

63.5 (30.0-95.0)

2.1 (3-1)

19.5 (14.5-23.5)

2.3 (1-5)

12.0 (11.8-12.1)

20-Sep

169

40%

.

.

19.0 (15.0-24.0)

2.4 (1-5)

12.0 (12.0-13.0)

Ambrosia

This is the third week this variety was tested. Ambrosia is still a new variety for the area, and we are learning about maturity for our region. Internal qualities indicate fruit is very near harvest maturity, but color is still less than excellent. It appears to be a heavy ethylene producing apple, with many fruit producing significant amounts in our sample last week and again this week. Starch clearing is difficult to interpret, with an interesting mosaic pattern. Clearing appears to begin throughout the flesh even while some of the cortex is still not clear. Overall, this variety needs a little more time and may begin harvest as early as next week. In other areas that grow Ambrosia, they pick it about the same time as Red Delicious.

Ambrosia sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Ambrosia

Ridge3

212

100%

.

.

18.2

4.9

13.7

Ambrosia

Ridge4

199

100%

.

.

16.3

4.4

12.8

Average

 

206

100%

.

.

17.3

4.7

13.3

Max

 

 

 

.

.

21.5

7.0

14.0

Min

 

 

 

.

.

15.0

3.0

12.0

Recommended

 

 

 

 

 

 

 

 

Ambrosia weekly averages

Collection Date

Fruit Weight (g)

Ethylene (% Fruit >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-6)

Soluble Solids (°Brix)

13-Sep

220

70%

30.5 (10-45)

1.6 (2-1)

17.6 (15.0-20.9)

3.5 (1-6)

11.9 (11.3-12.5)

20-Sep

206

100%

.

.

15.7 (13.5-22.0)

5.5 (3-8)

14.2 (12.0-17.0)

Rome

A single sample was evaluated this week to stay ahead of early-maturity fruit. Overall, Rome is still very immature. Color is developing nicely but firmness, sugars, and starch indicate it still needs more time. Model predicted harvest was Oct. 14, and we anticipate it to be close to accurate but like everything else this season, they might come in slightly earlier. There was no color bleeding in any of the Romes we sampled.

Rome sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Rome

Ridge3

180

0%

78.5

3.0

24.5

2.7

11.3

Average

 

180

0%

78.5

3.0

24.5

2.7

11.3

Max

 

 

 

90.0

3.0

27.0

3.0

11.3

Min

 

 

 

60.0

3.0

23.0

2.0

11.3

Recommended

 

 

 

 

 

15-18

3-5.5

 

Fuji

A few samples were tested this week to stay ahead of the early maturity that we have observed in other fruit. Overall, Fuji is still very immature. Color is still developing and pressures are high. Starch is beginning to clear. This variety does not stain well with iodine, and starch pattern fades quickly. Some internal ethylene is being produced already. Model-predicted harvest was Oct. 20, but we anticipate actual harvest date to be considerably earlier – especially if color improves.

Fuji sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Fuji

Belding1

210

40%

24.5

3.0

19.8

2.7

13.9

Fuji

Belding3

240

60%

68.0

4.0

20.6

2.5

11.9

Fuji

Ridge2

169

40%

.

.

18.3

2.7

13.8

Fuji

Ridge4

200

80%

.

.

19.7

2.0

13.4

Average

 

205

55%

46.3

3.5

19.6

2.5

13.3

Max

 

 

 

80.0

4.0

23.2

4.0

15.0

Min

 

 

 

5.0

3.0

14.5

1.0

11.9

Recommended

 

 

 

 

 

16-18

3-7

 

Evercrisp

A few samples were tested this week to stay ahead of the early maturity that we have observed in other fruit. Overall, Evercrisp is still very immature. Very little red color development has taken place and background color is very green. This is a high ethylene producing variety, which was detected in all samples. Starch clearing is just beginning. Soluble solids are high, which is a contribution of the Fuji background.

Evercrisp sampled Sept. 20

Variety

Location

Fruit Weight (g)

Ethylene (% >0.2ppm)

Red Color (%)

Background color (5-1)

Firmness (lbs)

Starch (1-7)

Soluble Solids (°Brix)

Evercrisp

Belding1

230

60%

22.0

4.0

22.6

1.8

11.4

Evercrisp

Belding3

220

100%

26.5

4.0

26.7

1.8

13.8

Evercrisp

Ridge4

305

60%

.

.

25.9

2.4

13.8

Evercrisp

Ridge2

177

70%

.

.

25.2

1.7

14.8

Average

 

233

73%

24.3

4.0

25.1

1.9

13.5

Max

 

 

 

40.0

4.0

31.1

4.0

15.5

Min

 

 

 

10.0

4.0

20.5

1.0

11.4

Recommended

 

 

 

 

 

 

 

 

Apple maturity sampling parameters

  • % 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
  • 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

7

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

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