Southwest Michigan apple maturity report – Sept. 6, 2017

Gala and Honeycrisp picking is underway. Light crop in some areas is speeding fruit harvesting.

General apple harvest comments

Dry conditions up to recent rains have been ideal for picking. Honeycrisp harvest has picked up considerably over the past week. Color and finish have been generally good, except where early frost damage marked fruit shortly after bloom.

Data in the following table is 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 Sept. 6

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Gala

18.2 (21.0-14.8)

4.1 (6.0-2.2)

12.9

Honeycrisp

14.4 (15.2-13.6)

5.7 (7.0-4.0)

13.1

Jonagold

16.5 (17.3-15.8)

5.2 (6.8-3.4)

12.0

Jonathan

17.9 (18.4-17.4)

3.2 (4.4-2.3)

13.0

Empire

17.0 (17.6-16.0)

2.1 (2.4-2.0)

12.2

Golden Delicious

18.7 (21.0-16.5)

1.4 (1.8-1.0)

12.7

Individual variety results

Gala harvest is proceeding rapidly. Gala are ripening rapidly with pressure averaging almost 3 pounds lower than last week, with the overall average at the long term CA storage value of 18. Most blocks tested have starch conversions readings testing internally mature (3 or above). Flavor and color have been generally very good. Some fruit are developing a waxy feel. The predicted harvest date for peak harvest for southwest Michigan in 2017 is August 25, which appears to be generally on target.

Honeycrisp maturity is moving steadily, with starch conversion averaging 5.7 compared to 3.9 for last week, above the target starch index of 3.5 or above recommended for good storage. Firmness averaged 14.4 pounds, about 1.5 less than last week, with some sites below the ideal of 16 for mid-term CA storage. As is the case with Honeycrisp, there is a wide range of ripening and some pre-harvest drop. Maturity is slightly ahead of the predicted peak harvest date of September 4 for central Berrien County for 2017, quite a bit ahead of the normal date of September 15. Skin blush ranged from 40 to 70% for standard Honeycrisp, with generally less bitter pit than normal, probably due to dry conditions. Precondition Honeycrisp fruit between 50 and 68 degrees Fahrenheit for 5 to 7 days before refrigeration to help avoid storage disorder problems.

Jonagold target starch index for fruit destined for fresh market is at least 3.5, and this week tested 5.2, quite a jump over last week’s 3.2. Current firmness of 16.5 pounds compared to last week’s 17.4 is averaging in the mid-term CA storage window. The target harvest date for central Berrien County for Jonagold is Sept. 15, thus maturity is moving ahead of predicted harvest, likely due to light crop loads and dry conditions.

Jonathan predicted peak harvest date for central Berrien County is Sept. 15. The current starch test is 3.2, close to the 3.5 considered mature for successful CA storage. Firmness is averaging 17.9 pounds, still above the borderline of 16 pounds between long and mid-term CA storage. Some Jonathans are being harvested for taffy apples.

Empire starch conversion reading this week is 2.1, about the same as last week, compared to the target value of 3.5 for long-term controlled atmosphere storage and fruit are very firm at an average of 17 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.

Golden Delicious were tested for the first time this week with firmness at 18.7 pounds and starch conversion still very immature at 1.4.  Some Goldens have been harvested for processing use.

Predicted peak fresh market apple harvest dates

The normal and estimated 2017 Peak harvest dates for apple varieties in southwest Michigan table is included here, as general guidelines. 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. Light crop and earlier dry conditions have also advanced maturity. 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

 

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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