Grand Rapids area apple maturity report – Oct. 7, 2020

October is apple month and there are so many varieties to choose from this week.

Packing lines in the Grand Rapids area are very busy. Photo by Amy Irish-Brown, 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.

Most Honeycrisp harvest is winding up. Jonathans and Jonagolds are nearly done. Many Golden Delicious and Red Delicious are finding bins this week. Our early samples of Fuji and Evercrisp show these varieties are moving faster in maturity this year than we normally see. It is likely due to the bright, sunny days and cool nights leading to good color, which is often what we are waiting for in these “late” varieties. Randy Beaudry of Michigan State University’s Department of Horticulture tells me he always thinks of Fuji as being shortly after Red Delicious, but we always seem to be waiting for color, so we delay picking. These same weather conditions can lead to higher incidence of water core, so be ready to harvest sooner rather than later for Fuji and Evercrisp, which are very prone to water core.

Normal and 2020 peak harvest dates for varieties for the Grand Rapids area

Variety

Normal date

2020 predicted date

Paulared

Aug. 24

Aug. 28

Gingergold

Aug. 26

Aug. 30

Gala

Sept. 10

Sept. 14

McIntosh

Sept. 15

Sept. 19

Honeycrisp

Sept. 18

Sept. 23

Empire

Sept. 24

Sept. 28

Jonathan

Sept. 26

Sept. 30

Jonagold

Sept. 26

Sept. 30

Golden Delicious

Oct. 2

Oct. 2

Red Delicious

Oct. 5

Oct. 6

Idared

Oct.10

Oct. 11

Rome

Oct. 15

Oct. 16

Fuji

Oct. 25

Oct. 26

Braeburn

Oct. 25

Oct. 26

Goldrush

Nov. 1

Nov. 2

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.

Our predicted harvest date for both Jonathan and Jonagold was Sept. 30 and many have been harvested in the last week. Maturity parameters this week have changed only slightly for these varieties in our samples. It is likely fruit will move to a mid-term controlled atmosphere (CA) window by the end of the week, especially if not treated with ReTain.

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)

Oct. 5+ ReTain

70

95 (95-100)

1

14.8 (13-16.5)

7

15.2 (15-16)

 

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)

Oct. 5+ ReTain

90

94 (90-100)

1

17 (15-18.5)

6.9 (6-7)

15 (14.5-15.5)

Cortland is just entering the mature window and depending on what your market is, they can begin to be harvested. Harvest of Cortland is usually between Jonagold and Red Delicious, which looks to 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

Oct. 5+ ReTain

100

92.5 (90-95)

1.6 (1-2)

14.5 (13.5-16)

4.4 (2-6)

14.1 (13.5-15)

Our sampled blocks for Golden Delicious and Red Delicious have been picked as have many blocks on the Ridge. There are reports of water core in Red Delicious.

Our predicted harvest date for Ida Red is Oct. 11. This week’s sample shows only a slight movement forward in maturity readings, but Oct. 11 will be a good target. Keep in mind our samples were treated with ReTain.

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)

Oct. 5+ ReTain

50

82.5 (25-95)

2.4 (2-3)

15.6 (14-17)

1.9 (1-3)

13.9 (13.5-14)

This is our first week to sample Rome and they are still immature. Our predicted harvest date for the Grand Rapids area is Oct. 16. Color, firmness and brix are all nearing the range of early maturity, but they need some time to size up a bit.

Rome 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)

Oct. 5

0

94.5 (90-95)

1.6 (1-2)

24.1 (21-31)

3

14.2 (14-15)

Our first Fuji sample is from a block of Aztec Fuji. On our MSU apple maturity team call this morning, there was much discussion about how far ahead Fuji are compared to our Oct. 26 predicted harvest date. Beaudry reminded us that they should be harvested for long-term CA soon after Red Delicious, but we often let them hang longer to get better color. Color is outstanding in 2020, as are brix and firmness, so keep an eye on Fuji for earlier than normal harvest. Newer strains also have better color adding to the harvest date confusion for this variety.

Also, the 2020 fall weather could be setting us up for more watercore than normal in Fuji. The best way to deal with watercore is to harvest fruit early and move it through the marketing chain. Fuji was bred specifically for its watercore and the sweetness it provides—not something conducive for long-term storage unfortunately.

Aztec Fuji 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)

Oct. 5

50

77 (60-90)

2.1 (2-3)

18.5 (15.5-20.5)

5 (3-6)

15 (13-16)

Evercrisp, like Fuji, seems to be much farther ahead in maturity than in recent years. It too will likely be able to be harvested early rather than later. This is good news as in recent years, harvest was toward the very end of October before that ruddy, green-brown background color faded. This year, the red color is much more pronounced and Evercrisp is quite pretty, even this early. This variety is also very prone to water core, so keep an eye on that.

Evercrisp 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)

Oct. 5

100

74 (40-90)

2.6 (2-4)

24 (21-27.5)

2.8 (2-3)

15.8 (15-16)

There are very few Granny Smith in the Grand Rapids area and they are still immature, but farther along in development that we are used to. Of note, our sample this week had very high incidence of watercore, something I didn’t even think Granny Smith had. We always pick them so immature, even at the end of October, that maybe we just never see it.

Granny Smith 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)

Oct. 5

0

15.5 (5-25)

3.1 (3-4)

19.1 (15.5-21)

2.9 (2-3)

14.1 (13.5-14.5)

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

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