Grand Rapids area apple maturity report – Sept. 30, 2020

This is a big week for Gala and Honeycrisp harvest in the Grand Rapids, Michigan, area.

Honeycrisp apples
Fruit color is outstanding this year as seen in this picture of Honeycrisp. Photo by Phil Schwallier, MSU Extension.

General comments

In the Grand Rapids, Michigan, area, apple maturity continues to run close to or slightly ahead of our 2020 predicted apple harvest dates for many varieties. Keep in mind these predicted dates are for peak harvest, so some fruits might be ready ahead or behind these dates as we move through maturity. Fruit color, finish, firmness and brix levels are all very good to excellent in 2020 for all varieties tested.

Brown marmorated stink bug damage continues to be found in various apple blocks, and numbers seem to increase week to week in our traps. Still, numbers are not in the crazy, outrageous level seen in the eastern United States.

Variety sampling results

Strains are noted where applicable. We try our best to collect samples from blocks untreated with harvest management products, but this week many samples had ReTain applied.

A great deal of the Gala blocks on the Ridge have been harvested. The only fruit we had left to sample has been treated with ReTain. Treated fruits are moving quickly to a short-term controlled atmosphere (CA) storage window and should be harvested soon.

Gala 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure (range)

Starch (range)

Brix (range)

Sept. 1

90

97 (90-100)

1

25.7 (20-34)

4.6 (1-8)

14.4 (13-16)

Sept. 7

100

94 (85-100)

1

21.4 (18-26)

4.2 (3-7)

14.2 (13-16)

Sept. 15

100

95 (90-100)

1

19.3 (16.5-23)

5.1 (1-8)

15.4 (14-16)

Sept. 22 + ReTain

100

98 (90-100)

1

18.7 (13-22.5)

6.8 (4-8)

17.1 (16-18)

Sept. 29 + ReTain

100

98 (90-100)

1

19.4 (13-27)

6.3 (4-8)

16.5 (16-17)

The predicted harvest date for peak harvest of Empire in Grand Rapids was Sept.r 28. This variety is in perfect condition for long-term CA storage. Empire harvest should go quickly as there are many less acres than 10 years ago.

Empire 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 7

0

50 (20-70)

3

20.3 (18-26)

1.9 (1-3)

12.8 (12-13)

Sept. 15

0

61.5 (40-80)

1.9 (1-2)

20.4 (17-25)

2.3 (1-3)

11.7 (11-12.5)

Sept. 22

0

76 (45-90)

2.8 (2-3)

18 (16-20.5)

3.3 (3-4)

12.7 (12-13.5)

Sept. 29 + ReTain

10

84 (45-100)

2.1 (1-3)

16.6 (14-18.5)

4 (2-6)

13.3 (13-14)

Our predicted harvest date for both Jonathan and Jonagold is today, Sept. 30. Both varieties are being harvested this week. For both Jonathan and Jonagold, fruit color is good to excellent depending on the strain. Starch clearing and other maturity parameters indicate the target window for untreated fruit to go into long-term CA is right now. Our samples are treated with ReTain and even this fruit shows they are in the perfect window for long-term CA storage and will likely move to a mid-term window in the next few days in the general Grand Rapids area.

Jonathan 2020 maturity sampling records (variety sampled is Jonee)

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 15

30

98.5 (90-100)

1.5 (1-2)

18.1 (15-20)

3.2 (3-4)

13.5 (12.5-14)

Sept. 22

100

98 (90-100)

1.3 (1-2)

17.1 (15-19.5)

4.9 (3-6)

14

Sept. 29 + ReTain

90

95 (95-100)

1

15.8 (14-18)

6.4 (5-7)

14.5 (14-16)

 

Jonagold 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 15

0

49.5 (40-75)

2.4 (2-3)

17.5 (15-21)

3.5 (2-6)

13.4 (12-15)

Sept. 22

80

63 (40-80)

2.6 (2-3)

16.9 (14-20)

5.5 (4-7)

14.5 (14-15.5)

Sept. 29 + ReTain

90

99 (95-100)

1

17.6 (16-21)

6

14.3 (14-15)

Cortland is still immature, and they continue to slowly move forward in maturity this week. Color continues to be excellent at 94%. The background color is less green at 1.4 compared to 2.2 last week. Cortland harvest is usually between Jonagold and Red Delicious and they need some time yet to mature, so that timing will be a good target for 2020.

Cortland 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 15

0

82 (50-90)

NA

17.2 (16-19)

1

13.4 (13-14)

Sept. 22

90

92 (85-100)

2.2 (2-3)

16.7 (13-19)

1.9 (1-2)

13.7 (13-14.5)

Sept. 29 + ReTain

90

94.5 (90-95)

1.4 (1-2)

15.8 (13.5-17.5)

2.7 (2-4)

14

The predicted harvest date for Grand Rapids area Golden Delicious is Oct. 2 and this is a good target to start on Goldens. Very few have been harvested. Our samples so far have been all treated with ReTain and this is holding internal ethylene numbers to very low and less than the 0.2 ppm climacteric. Many Goldens have a red blush this season due the great coloring weather. All readings, background color, firmness, starch clearing and brix, indicate that Golden Delicious is now entering long-term CA storage qualities

Golden Delicious 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 22 + ReTain

0

12 (0-30)

2.1 (2-3)

17.8 (16-20)

2 (1-4)

15.2 (14-16)

Sept. 29 + ReTain

0

10 (1-20)

2

17.1 (14-19.5)

2.5 (2-4)

16.4 (15-17)

This is our second week to look at Red Delicious. Fruits are still on the immature side but have shifted slightly. Our predicted harvest date for Reds is Oct. 6 for peak harvest for the Grand Rapids area and this date is likely to be a good target for long-term CA storage. Firmness is very good at 17.1 pounds this week. Starch readings are very low at 1.7, which is not unusual for Red Delicious. Brix levels are outstanding in Reds at 14.4, improved even more from 12.3 last week. Moldy core does not seem to be an issue in 2020 as it has been in the past few years—dry weather after bloom is likely the reason.

Red Delicious 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 22

0

85 (70-100)

1.6 (1-2)

19.4 (16.5-23)

2 (1-4)

12.3 (12-13)

Sept. 29 + ReTain

20

90.5 (70-100)

1.7 (1-2)

17.1 (14-21)

1.7 (1-4)

14.4 (14-15)

Our predicted harvest date for Ida Red is Oct. 11. Our first sample this week was treated with ReTain, so keep that in mind. Ida Reds untreated with ReTain or Harvista could be harvested in the next week or so where color is adequate. This variety might come in a bit earlier than our Oct. 11 predicted date. There are many less acres of Ida Reds than 10 years ago, so get to them in the next 10 days and they should be fine.

Ida Red 2020 maturity sampling records

Date of sample

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 29 + ReTain

0

71 (45-90)

2.3 (1-4)

16.8 (14-19)

1.9 (1-2)

13.3 (12.5-14)

Many changes in apple physiology occur over time as fruit become more mature—starch is converted to sugar; seeds turn a darker color; acidity decreases; chlorophyll levels decrease; respiration increases; cell walls weaken, fruit begins to soften; and ethylene production increases. Our MSU Ridge Apple Quality Lab and the MSU campus Beaudry Lab measure these and many other factors to help you make harvest management decisions:

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
  • Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
  • Brix = % sugar

We are graciously funded by the Michigan Tree Fruit Commission, Michigan Apple Committee, Michigan State Horticultural Society and Michigan State University Extension. Many thanks to all the growers and industry representatives that donate to our program.

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

Did you find this article useful?


You Might Also Be Interested In