Southwest Michigan apple maturity report – Sept. 9, 2020

Gala harvest is underway and Honeycrisp is ripening quickly. Honeycrisp fruit are showing wide range of internal maturity.

Mature Gala fruit showing stem end cracking and limb rub damage
Mature Gala fruit showing stem end cracking and limb rub damage. Photo by an anonymous grower.

General apple harvest comments

Southwest growers have been selectively harvesting Gala, Empire and Jonathan. Honeycrisp internal maturity (starch reading) is quite variable from fruit to fruit.

Woolly apple aphid colonies are becoming more common in some orchards and their honeydew and cottony fibers can cause contamination of apple fruit and foliage and annoy harvesting crews. Brown marmorated stink bugs are slowly becoming more common in apple orchards, with trap catches at significant levels in some hot spots. Trap catches for oriental fruit moth, codling moth and obliquebanded leafroller are still significant in some orchards, indicating some orchards need continued protection.

Fruit are generally clean of sooty blotch and flyspeck disease symptoms, but are common on unprotected fruit in abandoned orchards, indicating that fungicide protection has been needed. Orchards showing bitter rot problems will need more thorough fungicide protection than the normal summer disease program for sooty blotch and flyspeck.

Samples collected for this report are from the central Berrien County region, targeting more mature fruit on the outside of the tree canopy. Fruit in the interior of the tree will be less advanced than shown here. Sites with heavier soils and greater crop loads will generally be less mature.

The predicted harvest dates are based on temperatures from spring to 30 days after bloom and do not take into account summer temperatures, which can push development earlier or later than predicted. Hot weather over the past 30 days has stimulated internal ethylene levels in apple fruit and pushed along apple development.

Apple maturity in southwest Michigan for apples harvested Sept. 7, 2020

Variety

Firmness lbs. (range)

Starch (range)

Brix %

McIntosh

16.0 (16.0-16.0)

3.3 (3.0-3.6)

12.1

Gala

20.6 (18.3-23.0)

4.3 (2.0-6.4)

11.5

Honeycrisp

19.0 (18.9-19.0)

1.3 (1.0-1.8)

12.1

Empire

20.4 (18.0-23.0)

2.0 (1.4-2.4)

11.7

Jonathan

20.8 (20.0-22.0)

2.9 (2.4-3.0)

12.3

Jonagold

19.4 (18.2-21.0)

2.0 (2.0-2.0)

12.0

Individual variety results

McIntosh starch readings for the area now average 3.5, still below 5, the internal mature threshold. Firmness is averaging 15.5 pounds, the firmness recommended for long-term controlled atmosphere (CA) storage. Hot conditions have slowed blush development. The predicted harvest date for southwest Michigan in 2020 is Sept. 13.

McIntosh maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Aug. 31

16.0 (16.0-16.0)

3.3 (3.0-3.6)

12.1

Sept. 7

15.5 (15.0-16.0)

3.5 (3.0-4.0)

12.4

Gala starch readings indicate some orchards have fruit that are internally mature (3 or above), but still with excellent firmness that will allow harvest to be delayed if needed for better fruit size and sugar (brix). Skin color is generally good to very good, with some of the newer red strains nearly solid red. We are starting to see some stem end cracking on more mature fruit. The predicted harvest date for southwest Michigan in 2020 is Sept. 11. Hot weather is apparently pushing maturity a few days earlier than predicted.

Gala maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Aug. 31

20.6 (18.3-23.0)

4.3 (2.0-6.4)

11.5

Sept. 7

22.6 (22.0-23.0)

4.2 (3.6-5.0)

13.8

Honeycrisp starch readings are averaging 3.5 with a target mature starch index of 3.5 for this variety. Starch readings are quite variable from fruit to fruit at individual orchards, ranging from 1 to 7, indicating the need for spot picking. The current average firmness of 17.1 is at the general guideline of 17 pounds for best long-term CA storage. The predicted peak harvest date is Sept. 15 for central Berrien County.

Honeycrisp maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Aug. 31

19.0 (18.9-19.0)

1.3 (1.0-1.8)

12.1

Sept. 7

17.1 (16.0-18.2)

3.5 (3.0-4.0)

12.4

Empire was sampled for the first week. Like Jonathan, this variety is generally utilized as taffy apples and as fresh apple slices. The target starch test for mature apples for apples destined for fresh market or fresh apple slices is 3.5 with a minimum firmness of 16 for long-term CA storage. Predicted harvest dates for fresh market for central Berrien County is Sept. 21, which seems to be about on track with the current average firmness of 20.4 and starch conversion test average of 2.0.

Empire maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 7

20.4 (18.0-23.0)

2.0 (1.4-2.4)

11.7

Jonathan was sampled for the first week. Like Empire, this variety is generally utilized as taffy apples and as fresh apple slices. The target starch test for mature apples for apples destined for fresh market or fresh apple slices is 3.5 with a minimum firmness of 16 for long-term CA storage. Predicted harvest dates for fresh market for central Berrien County is Sept. 24, which seems to be about on target with the current average firmness of 20.8 pounds and starch average of 2.9.

Jonathan maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 7

20.8 (20.0-22.0)

2.9 (2.4-3.0)

12.3

Jonagold was sampled for the first week. Starch conversion this week is averaging 2.0, with 3.5 as the target for mature for this variety. Fruit firmness this week averaged 19.4 pounds, with the general guideline of a minimum of 17 pounds firmness for best long-term CA storage. The predicted peak harvest date is Sept. 24 for central Berrien County. The Jonagold crop is generally light in the area.

Jonagold maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 7

19.4 (18.2-21.0)

2.0 (2.0-2.0)

12.0

 

Normal and predicted 2020 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 in Benton Harbor, Michigan.

Variety

Normal date

2019 Predicted peak harvest date

2020 Predicted peak harvest date

Paula Red

Aug. 22

Aug. 28

Aug. 25

Zestar

Aug. 22

Aug. 28

Aug. 25

Gingergold

Aug. 20

Aug. 26

Aug. 23

McIntosh

Sept. 10

Sept. 16

Sept. 13

Gala

Sept. 8

Sept. 14

Sept. 11

Early Fuji

Sept. 3

Sept. 10

Sept. 6

Honeycrisp

Sept. 13

Sept. 20

Sept. 15

Empire

Sept. 19

Sept. 26

Sept. 21

Jonathan

Sept. 22

Sept. 30

Sept. 24

Jonagold

Sept. 22

Sept. 30

Sept. 24

Golden Delicious

Sept. 25

Oct. 1

Sept. 27

Red Delicious

Sept. 28

Oct. 7

Sept. 30

Ida Red

Oct. 5

Oct. 15

Oct. 7

Rome

Oct. 5

Oct. 15

Oct. 7

Fuji

Oct. 20

Oct. 28

Oct. 22

Braeburn

Oct. 20

Oct. 28

Oct. 2

Goldrush

Oct. 26

Nov. 3

Oct. 28

 

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

*Firmness is measured with a mechanical 11-millimeter wide probe inserted into the pared flesh of a fruit to a distance of 8 millimeters. Starch index is measured on equatorial cross section of an apple stained with iodine solution and rated using the Cornell University starch-iodine index chart for apples on a 1-8 scale (Predicting Harvest Date Window for Apples by Blanpied and Silsbey, Cornell Extension Bulletin 221.)

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.

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