Southwest Michigan apple maturity report – September 7, 2016

Gala, McIntosh and some Honeycrisp are being picked in southwest Michigan. Growers are urged to check fruit because the ripening of some apple varieties is moving rapidly.

General apple harvest comments

Gala harvest has been underway in area orchards. Jonathans and some Empire are being picked for taffy apples. Some spot picking of Honeycrisp is taking place in sandy sites.

The normal and estimated 2016 peak harvest dates for apple varieties in southwest Michigan table is included at the end of this report. Data in the following tables are based on samples collected from commercial orchards in the central Berrien County area.

Apple maturity in southwest Michigan for apples harvested Sept. 6

Variety

Firmness Lbs. (range)

Starch (range)

Brix %

McIntosh

16.7 (16.3-17.2)

4.1 (3.4-4.8)

13.2

Gala

19.9 (17.6-22.0)

5.5 (4.2-6.4)

13.2

Honeycrisp

16.7 (16.2-18.1)

5.4 (4.8-6.2)

14.0

Individual variety results

McIntosh was sampled for the third week. The predicted peak harvest date for the Southwest Michigan Research and Extension Center in Benton Harbor, Michigan, is Aug. 30. Typically, a starch index test of 5 or more indicates that the fruit is mature and ready for harvesting.

McIntosh 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)1

Starch (range)

Brix %

Aug. 22

18.6 (18.6-18.7)

3.0 (3.0-3.0)

11.7

Aug. 29

17.6 (17.2-17.6)

2.8 (2.6-3.0)

13.0

Sept. 6

16.7 (16.3-17.2)

4.1 (3.4-4.8)

13.2

1Range is the observed low and high mean values.

Gala was sampled for the third week. The current average starch index of 5.5 is well over the minimum value of 3, which is considered mature enough for successful long term controlled atmosphere storage. The predicted peak harvest date based on the Southwest Michigan Research and Extension Center location is Aug. 28. Some waxiness has been detected for more mature sites.

Gala 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Aug. 22

26.5 (25.0-28.0)

1.0 (1.0-1.0)

11.5

Aug. 29

22.2 (22.0-22.4)

3.4 (3.2-3.6)

12.2

Sept. 6

19.9 (17.6-22.0)

5.5 (4.2-6.4)

13.2

Honeycrisp was sampled for the first time this week. Target starch index for this variety is 3.5 and the predicted peak harvest date for the Southwest Michigan Research and Extension Center Enviro-weather station is Sept. 3. All Honeycrisp sites tested mature for long-term controlled atmosphere storage; skin color ranged from poor to excellent. Some water core was detected. As is the case with Honeycrisp, there is a wide range of ripening. Brix of 14 is generally good.

Honeycrisp 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 6

16.7 (16.2-18.1)

5.4 (4.8-6.2)

14.0

Early Fuji were not tested, but are expected to be mature based on past experience. The predicted peak harvest date for the Southwest Michigan Research and Extension Center site is Aug. 23.

Predicted apple harvest dates

Michigan State University Enviro-weather has a new utility, the “Apple Maturity Model,” to predict harvest dates for three varieties for many locations across the state. The table below has been expanded to include more apple varieties for the southwest region using the weather data for the Southwest Michigan Research and Extension Center. You can adjust your predicted harvest dates based on your bloom dates or make adjustments to this expanded list based on the typical harvest dates at your farm. These predicted harvest dates are based on a long established formula using the bloom date and temperatures for 30 days post-bloom. These dates are only 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 2016 peak harvest dates for apple varieties in southwest Michigan based on SWMREC weather data

Variety

Normal date

2016 predicted date

Paula Red

8/22

8/12

Zestar

8/22

8/12

Gingergold

8/20

8/10

McIntosh

9/10

8/30

Gala

9/8

8/28

Early Fuji

9/3

8/23

Honeycrisp

9/13

9/3

Empire

9/18

9/12

Jonathan

9/22

9/16

Jonagold

9/22

9/16

Golden Delicious

9/25

9/19

Red Delicious

9/28

9/22

Ida Red

10/5

9/30

Rome

10/5

9/30

Fuji

10/20

10/14

Braeburn

10/20

10/14

Goldrush

10/26

10/20

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.

The Southwest Michigan Apple Harvest Report is produced by Bill Shane, fruit specialist, Southwest Michigan Research and Extension Center, Benton Harbor, Michigan. Email: .(JavaScript must be enabled to view this email address).

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