Southwest Michigan apple maturity report – Sept. 22, 2021

This is the fourth weekly apple maturity report for the southwest Michigan region.

Chart
Brown marmorated stink bug trap catch for southwest Michigan in 2021. Photo by Mike Reinke, MSU Extension.

This apple maturity report for the southwest Michigan region is sent out every week (usually on Wednesdays) following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

Highlights for this week

Apple maturity is rapid for mid- to early late season varieties Empire, Golden Delicious, Red Delicious and Fuji with some orchards ripe enough for start of harvest. Current harvesting work in Berrien County has focused on Empire, Jonathan and Golden Delicious for processing.

Brown marmorated stink bug activity increased significantly over the past week as seen in trap catches and on sunny sides of buildings. Borders of apple orchards close to woods, buildings and soybean fields are usual places where damage starts.

Detailed information by variety

Mac, Gala and Honeycrisp

No more reports for these three varieties, now at full maturity.

Jonagold

Jonagold were sampled for the third week. Starch indices average 4.9, a significant jump over 3.2, with four of five sites tested averaging over 3.5, and considered mature. Fruit firmness has dropped approximately 2 pounds since last week and is averaging 17.6 pounds, slightly above the long-term controlled atmosphere (CA) storage threshold of 17 pounds.

This variety is maturing ahead of the predicted harvest date of Sept. 25 for central Berrien County. However, Jonagold skin red blush development has been slow this season, which is a problem for fruit to be sold for fresh consumption, but not for processing. Some area Jonagold have been harvested for processing.

Jonagold – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

 

Soluble solids (°Brix)

1

20.4

90-95

3.2

15.0

2

15.2

15-60

6.4

12.5

3

16.4

40-90

5.0

14.9

4

16.0

50-75

5.6

13.4

5

20.0

40-85

4.4

15.2

Average

17.6

 

4.9

14.2

Max

20.4

 

6.4

15.2

Min

15.2

 

3.2

12.5

Recommended

17-15

 

3.5

 

 

Jonagold maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 7

20.7 (18.2-23.3)

2.2 (1.2-3.0)

12.6

Sept. 13

19.5 (16.2-23.0)

3.2 (2.0-4.6)

13.6

Sept. 20

17.6 (15.2-20.4)

4.9 (3.2-6.4)

14.2

Jonathan

This variety was sampled for the third week, with now the starch conversion testing at an average of 5.2 pounds—a sizable jump over last week. This week, three out of four sites tested starch conversion values above 3.5, indicating fruit are internally mature. Also, flesh firmness dropped 1 pound to 16.1, now at the level where fruit transition from long term CA quality to a level more suited for shorter term storage. Some Jonathan have been harvested for taffy apples.

Jonathan – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

18.1

60-85

3.0

13.8

2

15.0

40-85

3.8

13.6

3

15.3

60-98

6.4

13.7

4

16.0

40-95

7.4

12.6

Average

16.1

 

5.2

13.4

Max

18.1

 

7.4

13.8

Min

15.0

 

3.0

12.6

Recommended

16-14

 

3.5

 

 

Jonathan maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 7

20.0 (19.0-21.0)

3.3 (3.0-3.8)

12.2

Sept. 13

17.9 (17.1-19.2)

3.4 (3.0-4.0)

12.6

Sept. 20

16.1 (15.0-18.1)

5.2 (3.0-7.4)

13.4

Empire

This variety was sampled for the third week. Firmness dropped about 1 pound since last week but is still very good, now at an average of 16.3 pounds for the four sites. Starch conversion has reached 3.8, above the 3.5 considered to be the threshold for internally mature. Brix is averaging about 1% higher than last week. Harvesting for fresh consumption can be delayed a short while to wait for better sugar development. The predicted harvest date for central Berrien County is Sept. 21, a reasonably accurate prediction. Some Empire have been harvested for taffy apples

Empire – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

17.0

70-98

4.0

12.8

2

16.0

50-85

2.6

12.1

3

16.3

98-100

3.4

12.6

4

16.0

30-70

5.2

11.7

5

 

 

 

 

Average

16.3

 

3.8

12.3

Max

17.0

 

5.2

12.8

Min

16.0

 

3.4

10.0

Recommended

16-14

 

3.5

 

 

Empire maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 7

19.4 (17.4-22.1)

2.9 (2.0-4.0)

11.2

Sept. 13

17.5 (16.2-20.0)

3.4 (3.0-4.2)

11.2

Sept. 20

16.3 (16.0-17.0)

3.8 (3.4-5.2)

12.3

Golden Delicious

This variety was sampled for the second week. Firmness is testing an average of 17.4 pounds, about the same as last week. This is only slightly above 17, the lower range considered ideal for long term CA storage. Starch conversion average is 3.5, above the 3.0 considered to be point where fruit become internally mature. This variety appears to be slightly ahead of the predicted harvest date of Sept. 28 for central Berrien County.

Golden Delicious – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

16.0

0

2.6

12.5

2

17.0

10-15

3.0

13.4

3

19.0

20-30

3.8

13.8

4

17.0

0

2.8

12.5

5

16.2

5-10

4.8

12.4

6

19.1

15-30

3.8

14.1

Average

17.4

 

3.5

13.1

Max

19.1

 

4.8

14.1

Min

16.0

 

2.6

12.4

Recommended

17-15

 

3.0

 

 

Golden Delicious maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 13

17.6 (16.0-20.0)

2.9 (1.0-4.2)

12.0

Sept. 20

17.4 (16.0-19.1)

3.5 (2.6-4.8)

13.1

Red Delicious

This variety was sampled for the second week. Firmness is testing an average of 18.4, close to 18, the range for long term CA storage. Starch conversion for the five sites tested an average of 3.8, already over 2.5, considered to be the threshold for internally mature. All six sites sampled are testing mature. This variety appears to be considerably ahead of the predicted harvest date, which is Oct. 3 for central Berrien County.

Red Delicious – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

17.0

70-100

3.4

11.5

2

17.4

40-100

4.0

9.4

3

17.0

70-95

6.0

11.9

4

18.0

80-95

4.0

11.5

5

16.2

85-98

2.6

11.1

6

19.0

100

3.0

12.8

Average

17.4

 

3.8

11.4

Max

19.0

 

6.0

12.8

Min

16.2

 

2.6

9.4

Recommended

18-16

 

2.5

 

 

Red Delicious maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 13

18.4 (17.2-20.2)

2.8 (2.0-4.0)

10.2

Sept. 20

17.4 (16.2-19.0)

3.8 (2.6-6.0)

11.4

Fuji

This variety was sampled for the second time and flesh firmness is testing an average of 19.0 pounds, about 0.5 pounds lower this week, and still in the range recommended for fruit for long term CA storage. Starch conversion tested 3.0, right at the threshold for being considered internally mature. Red blush ranges from 10 to 85%. Fuji has a predicted harvest date of Sept. 28 for central Berrien County. This is a much earlier predicted date (about three weeks earlier) than in past years, due to a recalculation of the normal harvest date for this variety. The revised harvest date seems correct for central Berrien County.

Fuji (Main season) – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

19.0

40-80

3.0

13.5

2

16.1

45-85

4.0

11.8

3

19.0

15-20

3.0

11.9

4

21.0

60-80

2.0

13.4

5

20.0

10-25

3.0

12.2

Average

19.0

 

3.0

12.6

Max

21.0

 

4.0

13.8

Min

16.1

 

2.0

11.8

Recommended

18-16

 

3.0

 

 

Fuji maturity sampling for the harvest season

Sample date

Firmness pounds (range)

Starch (range)

Brix %

Sept. 13

17.5 (16.2-20.0)

3.4 (3.0-4.2)

11.2

Sept. 20

19.0 (16.1-21.0)

3.0 (2.0-4.0)

12.6

IdaRed

This variety was harvested for the first time this week and is predicted to be ready approximately Oct. 10 in central Berrien County. Fruit firmness is still excellent at an average of 18.1 pounds, with starch conversion testing an average of 2.0, well below the 3.5 considered internally mature. According to these tests, IdaRed harvest can be delayed. Some blocks have been harvested for processing.

IdaRed – Sampled Sept. 20, 2021

Site

Firmness (lbs)

Red color range (%)

Starch

Soluble solids (°Brix)

1

18.3

60-90

2.0

13.3

2

20.0

70-98

1.0

13.6

3

16.1

30-60

2.0

11.0

4

17.3

50-95

2.8

12.0

5

19.0

60-98

2.0

13.2

Average

18.1

 

2.0

12.6

Max

20.0

 

2.8

13.6

Min

16.1

 

1.0

11.0

Recommended

16-14

 

3.5

 

Additional notes

The newly named Midwest Apple Association variety Ludacrisp is testing 20 pounds firmness, starch index 3.0, with brix of 14.8. This variety originated from seed of open pollenated Honeycrisp and has some of the flesh texture of that variety but has a much more complex flavor. Evercrisp, the first release from this program, is still very immature with firmness of 25 pounds, starch index of 1.0, and brix of 12.2.

How to read the maturity tables

For each variety evaluated, each row in the data table is a different orchard block. Maximum and minimum values are the highest and lowest individual fruits evaluated for each. 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.

Firmness in pounds pressure = measured with a FT Penetrometer using a 7/16 inch (11 millimeters) diameter probe, peel removed; range is for the average at each site.

Starch: 1 = no starch conversion, 8 = No starch; range is for average of the sites. Using Cornell Starch Iodine Index Chart.

Brix = % sugar measured with Atago PAL-1 Pocket Refractometer

Additional apple maturity helps

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

 

Normal and predicted 2021 peak harvest dates for apple varieties in central Berrien County in southwest Michigan based on weather data at the Southwest Michigan Research and Extension Center, Benton Harbor, MI.

Variety

Normal date SW

2020 Predicted 1st significant harvest date

2021 Predicted 1st significant harvest date

Paula Red

22-Aug

25-Aug

13-Aug

Zestar

22-Aug

25-Aug

13-Aug

Gingergold

20-Aug

23-Aug

11-Aug

Early Fuji

3-Sep

6-Sep

25-Aug

Gala

8-Sep

11-Sep

31-Aug

McIntosh

10-Sep

13-Sep

1-Sep

Honeycrisp

13-Sep

15-Sep

4-Sep

Empire

18-Sep

21-Sep

21-Sep

Jonathan

22-Sep

24-Sep

25-Sep

Jonagold

22-Sep

24-Sep

25-Sep

Fuji

25-Sep

28-Oct

28-Sep

Golden Delicious

25-Sep

27-Sep

28-Sep

Red Delicious

28-Sep

20-Sep

3-Oct

Ida Red

5-Oct

7-Oct

10-Oct

Rome

5-Oct

7-Oct

10-Oct

Braeburn

20-Oct

22-Oct

25-Oct

Goldrush

26-Oct

28-Oct

27-Oct

Please note that the predictions are for the first significant harvest date rather than peak harvest. Also note that the normal harvest date for Fuji is approximately three weeks ahead of the normal date given in previous years reports. Newer strains of Fuji have much earlier and more extensive red blush development than older strains. In the past, harvest of Fuji was delayed past optimum internal maturity to wait for better blush development. This delay has resulted in increased storage problems, including watercore and internal browning.

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