Southwest Michigan apple maturity report – Aug. 30, 2017

McIntosh and Gala harvest are underway. Apple maturity is running ahead of long-term normal dates.

General apple harvest comments

McIntosh and Gala harvest are underway in some area orchards. Jonathans and some Empire are being picked for taffy apples. Brown marmorated stink bug activity in commercial apple blocks is low, but more trouble is expected this year than last.

The normal and estimated 2017 peak harvest dates for apple varieties in southwest Michigan table is included at the end of this report. Predicted harvest dates for early season apple varieties are 10 to 15 days ahead of normal due to warm temperatures in the month following bloom. Data in the following tables are based on samples collected from commercial orchards in the central Berrien County area. Firmness and starch ranges are the observed low and high mean values.

Apple maturity in southwest Michigan for apples harvested Aug. 28 & 29

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Gala

21.0 (25.0-16.0)

3.6 (5.8-2.0)

12.2

Honeycrisp

16.1 (19.0-15.0)

3.9 (6.4-1.8)

12.8

Jonagold

17.4 (18.0-16.4)

3.2 (4.8-2.0)

11.4

Jonathan

20.0 (22.0-19.0)

2.4 (3.0-2.0)

11.8

Empire

18.0 (19.0-17.0)

2.4 (2.8-2.0)

11.5

Individual variety results

Gala starch readings indicate some orchards have fruit that are internally mature (3 or above), but with excellent firmness that will allow harvest to be delayed to wait for better fruit size and sugar (brix). Dry conditions in many southwest area orchards have slowed fruit sizing. Skin color is generally good to very good, with some of the newer red strains nearly solid red. The predicted harvest date for southwest Michigan in 2017 is Aug. 25.

Honeycrisp starch conversion tests are averaging 3.9 this week, above the target starch index of 3.5 or above for good storage, although a wide range of starch tests were measured in area orchards. Firmness averaged 16.1, slightly below the ideal of 17 for long-term controlled atmosphere (CA) storage. As is the case with Honeycrisp, there is a wide range of ripening and some pre-harvest drop. The predicted peak harvest date for central Berrien County for 2017 is Sept. 4, quite a bit ahead of the normal date of Sept. 15. Skin color ranged from poor to excellent, with the newer red strains such as Royal Red looking good.

Jonagold background color was generally green and the fruit taste green as well. Target starch index for fruit destined for fresh market is at least 3.5, and this week tested 3.2. Current firmness of 17.4 is still good and harvest can wait for more starch conversion and skin color development for fruit intended for fresh market. The target harvest date for central Berrien County for Jonagold is Sept. 15. Crop loads for Jonagold are generally light in the area due to cool temperatures during bloom.

Jonathan predicted peak harvest date for central Berrien County is Sept. 15. The current starch test is 2.4, which is considered immature for successful CA storage. Firmness is averaging 20 pounds, which is very firm. Some Jonathans are being harvested for taffy apples.

Empire starch conversion reading this week is 2.4 compared to the target value of 3.5 for long-term CA storage and fruit are very firm at an average of 18 pounds. Background color is green. The predicted peak harvest date is Sept. 10 for fresh market for central Berrien County. Good firmness will allow harvest to be delayed for better fruit quality development for fresh market and for higher quality processing uses.

Predicted peak fresh market apple harvest dates

These dates are an estimate and will be affected by the apple strain, rootstock, crop load, fertility, soil type and other factors including current weather.

Normal and predicted 2017 peak harvest dates for apple varieties in southwest Michigan based on SWMREC weather data.

Variety

Normal date

2017 predicted date

Paula Red

Aug. 22

Aug. 7

Zestar

Aug. 22

Aug. 7

Gingergold

Aug. 20

Aug. 9

McIntosh

Sept. 10

Aug. 29

Gala

Sept. 8

Aug. 25

Early Fuji

Sept. 3

Aug. 24

Honeycrisp

Sept. 13

Sept. 4

Empire

Sept. 19

Sept. 10

Jonathan

Sept. 22

Sept. 15

Jonagold

Sept. 22

Sept. 15

Golden Delicious

Sept. 25

Sept. 19

Red Delicious

Sept. 28

Sept. 22

Ida Red

Oct. 5

Sept. 30

Rome

Oct. 5

Sept. 30

Fuji

Oct. 20

Oct. 15

Braeburn

Oct. 20

Oct. 15

Goldrush

Oct. 26

Oct. 21

Source: R. Beaudry, P. Schwallier, and M. Lennington. 1993. Apple maturity prediction: an extension tool to aid fruit storage decisions. HortTechnology 3:233-239.

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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